diff --git a/pkg/dev_compiler/lib/runtime/dart/_foreign_helper.js b/pkg/dev_compiler/lib/runtime/dart/_foreign_helper.js
index da5466e74464..02764210101f 100644
--- a/pkg/dev_compiler/lib/runtime/dart/_foreign_helper.js
+++ b/pkg/dev_compiler/lib/runtime/dart/_foreign_helper.js
@@ -34,13 +34,13 @@ var _foreign_helper;
   class IsolateContext extends core.Object {
   }
   // Function JS_CALL_IN_ISOLATE: (dynamic, Function) → dynamic
-  function JS_CALL_IN_ISOLATE(isolate, function) {
+  function JS_CALL_IN_ISOLATE(isolate, func) {
   }
   // Function DART_CLOSURE_TO_JS: (Function) → dynamic
-  function DART_CLOSURE_TO_JS(function) {
+  function DART_CLOSURE_TO_JS(func) {
   }
   // Function RAW_DART_FUNCTION_REF: (Function) → dynamic
-  function RAW_DART_FUNCTION_REF(function) {
+  function RAW_DART_FUNCTION_REF(func) {
   }
   // Function JS_SET_CURRENT_ISOLATE: (dynamic) → void
   function JS_SET_CURRENT_ISOLATE(isolate) {
diff --git a/pkg/dev_compiler/lib/runtime/dart/_interceptors.js b/pkg/dev_compiler/lib/runtime/dart/_interceptors.js
index 24e0d164de7c..062285cd427f 100644
--- a/pkg/dev_compiler/lib/runtime/dart/_interceptors.js
+++ b/pkg/dev_compiler/lib/runtime/dart/_interceptors.js
@@ -168,12 +168,12 @@ var _interceptors;
       fold(initialValue, combine) {
         return _internal.IterableMixinWorkaround.fold(this, initialValue, combine);
       }
-      firstWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      firstWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         return dart.as(_internal.IterableMixinWorkaround.firstWhere(this, test, orElse), E);
       }
-      lastWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      lastWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         return dart.as(_internal.IterableMixinWorkaround.lastWhereList(this, test, orElse), E);
       }
       singleWhere(test) {
@@ -298,8 +298,8 @@ var _interceptors;
       toString() {
         return collection.ListBase.listToString(this);
       }
-      toList(opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      toList(opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         if (growable) {
           return new JSArray.markGrowable(this.slice());
         } else {
@@ -372,7 +372,7 @@ var _interceptors;
     return JSExtendableArray;
   });
   let JSExtendableArray = JSExtendableArray$(dart.dynamic);
-  let _handleIEtoString = Symbol('_handleIEtoString');
+  let _handleIEtoString$ = Symbol('_handleIEtoString');
   let _isInt32 = Symbol('_isInt32');
   let _tdivFast = Symbol('_tdivFast');
   let _tdivSlow = Symbol('_tdivSlow');
@@ -536,7 +536,7 @@ var _interceptors;
       }
       return _handleIEtoString(result);
     }
-    static [_handleIEtoString](result) {
+    static [_handleIEtoString$](result) {
       let match = /^([\da-z]+)(?:\.([\da-z]+))?\(e\+(\d+)\)$/.exec(result);
       if (match === null) {
         throw new core.UnsupportedError(`Unexpected toString result: ${result}`);
@@ -687,11 +687,11 @@ var _interceptors;
   }
   JSNumber._MIN_INT32 = -2147483648;
   JSNumber._MAX_INT32 = 2147483647;
-  let _bitCount = Symbol('_bitCount');
-  let _shru = Symbol('_shru');
-  let _shrs = Symbol('_shrs');
-  let _ors = Symbol('_ors');
-  let _spread = Symbol('_spread');
+  let _bitCount$ = Symbol('_bitCount');
+  let _shru$ = Symbol('_shru');
+  let _shrs$ = Symbol('_shrs');
+  let _ors$ = Symbol('_ors');
+  let _spread$ = Symbol('_spread');
   class JSInt extends JSNumber {
     JSInt() {
       super.JSNumber();
@@ -717,7 +717,7 @@ var _interceptors;
       }
       return _bitCount(_spread(nonneg));
     }
-    static [_bitCount](i) {
+    static [_bitCount$](i) {
       i = dart.as(dart.dbinary(_shru(i, 0), '-', dart.dbinary(_shru(i, 1), '&', 1431655765)), core.int);
       i = (dart.notNull(i) & 858993459)['+'](dart.dbinary(_shru(i, 2), '&', 858993459));
       i = 252645135 & i['+'](_shru(i, 4));
@@ -725,16 +725,16 @@ var _interceptors;
       i = dart.as(_shru(i, 16), core.int);
       return dart.notNull(i) & 63;
     }
-    static [_shru](value, shift) {
+    static [_shru$](value, shift) {
       return value >>> shift;
     }
-    static [_shrs](value, shift) {
+    static [_shrs$](value, shift) {
       return value >> shift;
     }
-    static [_ors](a, b) {
+    static [_ors$](a, b) {
       return a | b;
     }
-    static [_spread](i) {
+    static [_spread$](i) {
       i = dart.as(_ors(i, dart.as(_shrs(i, 1), core.int)), core.int);
       i = dart.as(_ors(i, dart.as(_shrs(i, 2), core.int)), core.int);
       i = dart.as(_ors(i, dart.as(_shrs(i, 4), core.int)), core.int);
@@ -764,9 +764,9 @@ var _interceptors;
   class JSUInt31 extends JSUInt32 {
   }
   let _defaultSplit = Symbol('_defaultSplit');
-  let _isWhitespace = Symbol('_isWhitespace');
-  let _skipLeadingWhitespace = Symbol('_skipLeadingWhitespace');
-  let _skipTrailingWhitespace = Symbol('_skipTrailingWhitespace');
+  let _isWhitespace$ = Symbol('_isWhitespace');
+  let _skipLeadingWhitespace$ = Symbol('_skipLeadingWhitespace');
+  let _skipTrailingWhitespace$ = Symbol('_skipTrailingWhitespace');
   class JSString extends Interceptor {
     JSString() {
       super.Interceptor();
@@ -824,9 +824,9 @@ var _interceptors;
     replaceAllMapped(from, convert) {
       return this.splitMapJoin(from, {onMatch: convert});
     }
-    splitMapJoin(from, opt$) {
-      let onMatch = opt$ && 'onMatch' in opt$ ? opt$.onMatch : null;
-      let onNonMatch = opt$ && 'onNonMatch' in opt$ ? opt$.onNonMatch : null;
+    splitMapJoin(from, opts) {
+      let onMatch = opts && 'onMatch' in opts ? opts.onMatch : null;
+      let onNonMatch = opts && 'onNonMatch' in opts ? opts.onNonMatch : null;
       return dart.as(_js_helper.stringReplaceAllFuncUnchecked(this, from, onMatch, onNonMatch), core.String);
     }
     replaceFirst(from, to, startIndex) {
@@ -908,7 +908,7 @@ var _interceptors;
     toUpperCase() {
       return this.toUpperCase();
     }
-    static [_isWhitespace](codeUnit) {
+    static [_isWhitespace$](codeUnit) {
       if (dart.notNull(codeUnit) < 256) {
         switch (codeUnit) {
           case 9:
@@ -949,7 +949,7 @@ var _interceptors;
           return false;
       }
     }
-    static [_skipLeadingWhitespace](string, index) {
+    static [_skipLeadingWhitespace$](string, index) {
       let SPACE = 32;
       let CARRIAGE_RETURN = 13;
       while (dart.notNull(index) < dart.notNull(string.length)) {
@@ -961,7 +961,7 @@ var _interceptors;
       }
       return index;
     }
-    static [_skipTrailingWhitespace](string, index) {
+    static [_skipTrailingWhitespace$](string, index) {
       let SPACE = 32;
       let CARRIAGE_RETURN = 13;
       while (dart.notNull(index) > 0) {
@@ -1178,8 +1178,8 @@ var _interceptors;
   }
   let _string = Symbol('_string');
   class _CodeUnits extends _internal.UnmodifiableListBase$(core.int) {
-    _CodeUnits($_string) {
-      this[_string] = $_string;
+    _CodeUnits(string$) {
+      this[_string] = string$;
       super.UnmodifiableListBase();
     }
     get length() {
diff --git a/pkg/dev_compiler/lib/runtime/dart/_internal.js b/pkg/dev_compiler/lib/runtime/dart/_internal.js
index 2de7ea2dcc5a..9b0c19999565 100644
--- a/pkg/dev_compiler/lib/runtime/dart/_internal.js
+++ b/pkg/dev_compiler/lib/runtime/dart/_internal.js
@@ -73,8 +73,8 @@ var _internal;
         }
         return false;
       }
-      firstWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      firstWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         let length = this.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           let element = this.elementAt(i);
@@ -88,8 +88,8 @@ var _internal;
           return orElse();
         throw IterableElementError.noElement();
       }
-      lastWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      lastWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         let length = this.length;
         for (let i = dart.notNull(length) - 1; dart.notNull(i) >= 0; i = dart.notNull(i) - 1) {
           let element = this.elementAt(i);
@@ -197,8 +197,8 @@ var _internal;
       takeWhile(test) {
         return super.takeWhile(test);
       }
-      toList(opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      toList(opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         let result = null;
         if (growable) {
           result = ((_) => {
@@ -231,10 +231,10 @@ var _internal;
   let _startIndex = Symbol('_startIndex');
   let SubListIterable$ = dart.generic(function(E) {
     class SubListIterable extends ListIterable$(E) {
-      SubListIterable($_iterable, $_start, $_endOrLength) {
-        this[_iterable] = $_iterable;
-        this[_start] = $_start;
-        this[_endOrLength] = $_endOrLength;
+      SubListIterable(iterable$, start$, endOrLength) {
+        this[_iterable] = iterable$;
+        this[_start] = start$;
+        this[_endOrLength] = endOrLength;
         super.ListIterable();
         core.RangeError.checkNotNegative(this[_start], "start");
         if (this[_endOrLength] !== null) {
@@ -291,8 +291,8 @@ var _internal;
           return new SubListIterable(this[_iterable], this[_start], newEnd);
         }
       }
-      toList(opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      toList(opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         let start = this[_start];
         let end = this[_iterable].length;
         if (this[_endOrLength] !== null && dart.notNull(this[_endOrLength]) < dart.notNull(end))
@@ -349,15 +349,15 @@ var _internal;
   let _f = Symbol('_f');
   let MappedIterable$ = dart.generic(function(S, T) {
     class MappedIterable extends collection.IterableBase$(T) {
-      MappedIterable(iterable, function) {
+      MappedIterable(iterable, func) {
         if (dart.is(iterable, EfficientLength)) {
-          return new EfficientLengthMappedIterable(iterable, function);
+          return new EfficientLengthMappedIterable(iterable, func);
         }
-        return new MappedIterable._(dart.as(iterable, core.Iterable$(S)), function);
+        return new MappedIterable._(dart.as(iterable, core.Iterable$(S)), func);
       }
-      MappedIterable$_($_iterable, $_f) {
-        this[_iterable] = $_iterable;
-        this[_f] = $_f;
+      MappedIterable$_(iterable$, f$) {
+        this[_iterable] = iterable$;
+        this[_f] = f$;
         super.IterableBase();
       }
       get iterator() {
@@ -388,8 +388,8 @@ var _internal;
   let MappedIterable = MappedIterable$(dart.dynamic, dart.dynamic);
   let EfficientLengthMappedIterable$ = dart.generic(function(S, T) {
     class EfficientLengthMappedIterable extends MappedIterable$(S, T) {
-      EfficientLengthMappedIterable(iterable, function) {
-        super.MappedIterable$_(dart.as(iterable, core.Iterable$(S)), function);
+      EfficientLengthMappedIterable(iterable, func) {
+        super.MappedIterable$_(dart.as(iterable, core.Iterable$(S)), func);
       }
     }
     return EfficientLengthMappedIterable;
@@ -398,9 +398,9 @@ var _internal;
   let _iterator = Symbol('_iterator');
   let MappedIterator$ = dart.generic(function(S, T) {
     class MappedIterator extends core.Iterator$(T) {
-      MappedIterator($_iterator, $_f) {
-        this[_iterator] = $_iterator;
-        this[_f] = $_f;
+      MappedIterator(iterator$, f$) {
+        this[_iterator] = iterator$;
+        this[_f] = f$;
         this[_current] = null;
         super.Iterator();
       }
@@ -422,9 +422,9 @@ var _internal;
   let _source = Symbol('_source');
   let MappedListIterable$ = dart.generic(function(S, T) {
     class MappedListIterable extends ListIterable$(T) {
-      MappedListIterable($_source, $_f) {
-        this[_source] = $_source;
-        this[_f] = $_f;
+      MappedListIterable(source, f$) {
+        this[_source] = source;
+        this[_f] = f$;
         super.ListIterable();
       }
       get length() {
@@ -439,9 +439,9 @@ var _internal;
   let MappedListIterable = MappedListIterable$(dart.dynamic, dart.dynamic);
   let WhereIterable$ = dart.generic(function(E) {
     class WhereIterable extends collection.IterableBase$(E) {
-      WhereIterable($_iterable, $_f) {
-        this[_iterable] = $_iterable;
-        this[_f] = $_f;
+      WhereIterable(iterable$, f$) {
+        this[_iterable] = iterable$;
+        this[_f] = f$;
         super.IterableBase();
       }
       get iterator() {
@@ -453,9 +453,9 @@ var _internal;
   let WhereIterable = WhereIterable$(dart.dynamic);
   let WhereIterator$ = dart.generic(function(E) {
     class WhereIterator extends core.Iterator$(E) {
-      WhereIterator($_iterator, $_f) {
-        this[_iterator] = $_iterator;
-        this[_f] = $_f;
+      WhereIterator(iterator$, f$) {
+        this[_iterator] = iterator$;
+        this[_f] = f$;
         super.Iterator();
       }
       moveNext() {
@@ -475,9 +475,9 @@ var _internal;
   let WhereIterator = WhereIterator$(dart.dynamic);
   let ExpandIterable$ = dart.generic(function(S, T) {
     class ExpandIterable extends collection.IterableBase$(T) {
-      ExpandIterable($_iterable, $_f) {
-        this[_iterable] = $_iterable;
-        this[_f] = $_f;
+      ExpandIterable(iterable$, f$) {
+        this[_iterable] = iterable$;
+        this[_f] = f$;
         super.IterableBase();
       }
       get iterator() {
@@ -491,9 +491,9 @@ var _internal;
   let _nextExpansion = Symbol('_nextExpansion');
   let ExpandIterator$ = dart.generic(function(S, T) {
     class ExpandIterator extends core.Object {
-      ExpandIterator($_iterator, $_f) {
-        this[_iterator] = $_iterator;
-        this[_f] = $_f;
+      ExpandIterator(iterator$, f$) {
+        this[_iterator] = iterator$;
+        this[_f] = f$;
         this[_currentExpansion] = dart.as(new EmptyIterator(), core.Iterator$(T));
         this[_current] = null;
       }
@@ -532,9 +532,9 @@ var _internal;
         }
         return new TakeIterable._(iterable, takeCount);
       }
-      TakeIterable$_($_iterable, $_takeCount) {
-        this[_iterable] = $_iterable;
-        this[_takeCount] = $_takeCount;
+      TakeIterable$_(iterable$, takeCount$) {
+        this[_iterable] = iterable$;
+        this[_takeCount] = takeCount$;
         super.IterableBase();
       }
       get iterator() {
@@ -563,9 +563,9 @@ var _internal;
   let _remaining = Symbol('_remaining');
   let TakeIterator$ = dart.generic(function(E) {
     class TakeIterator extends core.Iterator$(E) {
-      TakeIterator($_iterator, $_remaining) {
-        this[_iterator] = $_iterator;
-        this[_remaining] = $_remaining;
+      TakeIterator(iterator$, remaining) {
+        this[_iterator] = iterator$;
+        this[_remaining] = remaining;
         super.Iterator();
         dart.assert(dart.notNull(typeof this[_remaining] == number) && dart.notNull(this[_remaining]) >= 0);
       }
@@ -588,9 +588,9 @@ var _internal;
   let TakeIterator = TakeIterator$(dart.dynamic);
   let TakeWhileIterable$ = dart.generic(function(E) {
     class TakeWhileIterable extends collection.IterableBase$(E) {
-      TakeWhileIterable($_iterable, $_f) {
-        this[_iterable] = $_iterable;
-        this[_f] = $_f;
+      TakeWhileIterable(iterable$, f$) {
+        this[_iterable] = iterable$;
+        this[_f] = f$;
         super.IterableBase();
       }
       get iterator() {
@@ -603,9 +603,9 @@ var _internal;
   let _isFinished = Symbol('_isFinished');
   let TakeWhileIterator$ = dart.generic(function(E) {
     class TakeWhileIterator extends core.Iterator$(E) {
-      TakeWhileIterator($_iterator, $_f) {
-        this[_iterator] = $_iterator;
-        this[_f] = $_f;
+      TakeWhileIterator(iterator$, f$) {
+        this[_iterator] = iterator$;
+        this[_f] = f$;
         this[_isFinished] = false;
         super.Iterator();
       }
@@ -636,9 +636,9 @@ var _internal;
         }
         return new SkipIterable._(iterable, count);
       }
-      SkipIterable$_($_iterable, $_skipCount) {
-        this[_iterable] = $_iterable;
-        this[_skipCount] = $_skipCount;
+      SkipIterable$_(iterable$, skipCount$) {
+        this[_iterable] = iterable$;
+        this[_skipCount] = skipCount$;
         super.IterableBase();
         if (!(typeof this[_skipCount] == number)) {
           throw new core.ArgumentError.value(this[_skipCount], "count is not an integer");
@@ -677,9 +677,9 @@ var _internal;
   let EfficientLengthSkipIterable = EfficientLengthSkipIterable$(dart.dynamic);
   let SkipIterator$ = dart.generic(function(E) {
     class SkipIterator extends core.Iterator$(E) {
-      SkipIterator($_iterator, $_skipCount) {
-        this[_iterator] = $_iterator;
-        this[_skipCount] = $_skipCount;
+      SkipIterator(iterator$, skipCount$) {
+        this[_iterator] = iterator$;
+        this[_skipCount] = skipCount$;
         super.Iterator();
         dart.assert(dart.notNull(typeof this[_skipCount] == number) && dart.notNull(this[_skipCount]) >= 0);
       }
@@ -698,9 +698,9 @@ var _internal;
   let SkipIterator = SkipIterator$(dart.dynamic);
   let SkipWhileIterable$ = dart.generic(function(E) {
     class SkipWhileIterable extends collection.IterableBase$(E) {
-      SkipWhileIterable($_iterable, $_f) {
-        this[_iterable] = $_iterable;
-        this[_f] = $_f;
+      SkipWhileIterable(iterable$, f$) {
+        this[_iterable] = iterable$;
+        this[_f] = f$;
         super.IterableBase();
       }
       get iterator() {
@@ -713,9 +713,9 @@ var _internal;
   let _hasSkipped = Symbol('_hasSkipped');
   let SkipWhileIterator$ = dart.generic(function(E) {
     class SkipWhileIterator extends core.Iterator$(E) {
-      SkipWhileIterator($_iterator, $_f) {
-        this[_iterator] = $_iterator;
-        this[_f] = $_f;
+      SkipWhileIterator(iterator$, f$) {
+        this[_iterator] = iterator$;
+        this[_f] = f$;
         this[_hasSkipped] = false;
         super.Iterator();
       }
@@ -772,20 +772,20 @@ var _internal;
       any(test) {
         return false;
       }
-      firstWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      firstWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         if (orElse !== null)
           return orElse();
         throw IterableElementError.noElement();
       }
-      lastWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      lastWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         if (orElse !== null)
           return orElse();
         throw IterableElementError.noElement();
       }
-      singleWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      singleWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         if (orElse !== null)
           return orElse();
         throw IterableElementError.noElement();
@@ -821,8 +821,8 @@ var _internal;
       takeWhile(test) {
         return this;
       }
-      toList(opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      toList(opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         return growable ? new List.from([]) : new core.List(0);
       }
       toSet() {
@@ -852,7 +852,7 @@ var _internal;
     return BidirectionalIterator;
   });
   let BidirectionalIterator = BidirectionalIterator$(dart.dynamic);
-  let _rangeCheck = Symbol('_rangeCheck');
+  let _rangeCheck$ = Symbol('_rangeCheck');
   let IterableMixinWorkaround$ = dart.generic(function(T) {
     class IterableMixinWorkaround extends core.Object {
       static contains(iterable, element) {
@@ -1088,7 +1088,7 @@ var _internal;
           start = dart.notNull(list.length) - 1;
         return Lists.lastIndexOf(list, element, start);
       }
-      static [_rangeCheck](list, start, end) {
+      static [_rangeCheck$](list, start, end) {
         core.RangeError.checkValidRange(start, end, list.length);
       }
       getRangeList(list, start, end) {
@@ -1156,13 +1156,13 @@ var _internal;
         list.length = insertionLength;
         list.setRange(dart.notNull(index) + dart.notNull(insertionLength), list.length, list, index);
         for (let element of iterable) {
-          list.set((($tmp) => index = dart.notNull($tmp) + 1, $tmp)(index), element);
+          list.set(((x) => index = dart.notNull(x$) + 1, x$)(index), element);
         }
       }
       static setAllList(list, index, iterable) {
         core.RangeError.checkValueInInterval(index, 0, list.length, "index");
         for (let element of iterable) {
-          list.set((($tmp) => index = dart.notNull($tmp) + 1, $tmp)(index), element);
+          list.set(((x) => index = dart.notNull(x$) + 1, x$)(index), element);
         }
       }
       asMapList(l) {
@@ -1350,8 +1350,8 @@ var _internal;
   let UnmodifiableListBase = UnmodifiableListBase$(dart.dynamic);
   let _backedList = Symbol('_backedList');
   class _ListIndicesIterable extends ListIterable$(core.int) {
-    _ListIndicesIterable($_backedList) {
-      this[_backedList] = $_backedList;
+    _ListIndicesIterable(backedList) {
+      this[_backedList] = backedList;
       super.ListIterable();
     }
     get length() {
@@ -1365,8 +1365,8 @@ var _internal;
   let _values = Symbol('_values');
   let ListMapView$ = dart.generic(function(E) {
     class ListMapView extends core.Object {
-      ListMapView($_values) {
-        this[_values] = $_values;
+      ListMapView(values) {
+        this[_values] = values;
       }
       get(key) {
         return this.containsKey(key) ? this[_values].get(key) : null;
@@ -1425,8 +1425,8 @@ var _internal;
   let ListMapView = ListMapView$(dart.dynamic);
   let ReversedListIterable$ = dart.generic(function(E) {
     class ReversedListIterable extends ListIterable$(E) {
-      ReversedListIterable($_source) {
-        this[_source] = $_source;
+      ReversedListIterable(source) {
+        this[_source] = source;
         super.ListIterable();
       }
       get length() {
@@ -1540,9 +1540,9 @@ var _internal;
   function printToConsole(line) {
     _js_primitives.printString(`${line}`);
   }
-  let _doSort = Symbol('_doSort');
-  let _insertionSort = Symbol('_insertionSort');
-  let _dualPivotQuicksort = Symbol('_dualPivotQuicksort');
+  let _doSort$ = Symbol('_doSort');
+  let _insertionSort$ = Symbol('_insertionSort');
+  let _dualPivotQuicksort$ = Symbol('_dualPivotQuicksort');
   class Sort extends core.Object {
     static sort(a, compare) {
       _doSort(a, 0, dart.notNull(a.length) - 1, compare);
@@ -1553,14 +1553,14 @@ var _internal;
       }
       _doSort(a, from, dart.notNull(to) - 1, compare);
     }
-    static [_doSort](a, left, right, compare) {
+    static [_doSort$](a, left, right, compare) {
       if (dart.notNull(right) - dart.notNull(left) <= dart.notNull(Sort._INSERTION_SORT_THRESHOLD)) {
         _insertionSort(a, left, right, compare);
       } else {
         _dualPivotQuicksort(a, left, right, compare);
       }
     }
-    static [_insertionSort](a, left, right, compare) {
+    static [_insertionSort$](a, left, right, compare) {
       for (let i = dart.notNull(left) + 1; dart.notNull(i) <= dart.notNull(right); i = dart.notNull(i) + 1) {
         let el = a.get(i);
         let j = i;
@@ -1571,7 +1571,7 @@ var _internal;
         a.set(j, el);
       }
     }
-    static [_dualPivotQuicksort](a, left, right, compare) {
+    static [_dualPivotQuicksort$](a, left, right, compare) {
       dart.assert(dart.notNull(right) - dart.notNull(left) > dart.notNull(Sort._INSERTION_SORT_THRESHOLD));
       let sixth = ((dart.notNull(right) - dart.notNull(left) + 1) / 6).truncate();
       let index1 = dart.notNull(left) + dart.notNull(sixth);
@@ -1660,12 +1660,12 @@ var _internal;
                 continue;
               } else if (dart.notNull(comp) < 0) {
                 a.set(k, a.get(less));
-                a.set((($tmp) => less = dart.notNull($tmp) + 1, $tmp)(less), a.get(great));
-                a.set((($tmp) => great = dart.notNull($tmp) - 1, $tmp)(great), ak);
+                a.set(((x) => less = dart.notNull(x$) + 1, x$)(less), a.get(great));
+                a.set(((x) => great = dart.notNull(x$) - 1, x$)(great), ak);
                 break;
               } else {
                 a.set(k, a.get(great));
-                a.set((($tmp) => great = dart.notNull($tmp) - 1, $tmp)(great), ak);
+                a.set(((x) => great = dart.notNull(x$) - 1, x$)(great), ak);
                 break;
               }
             }
@@ -1695,11 +1695,11 @@ var _internal;
                   comp = dart.dinvokef(compare, a.get(great), pivot1);
                   if (dart.notNull(comp) < 0) {
                     a.set(k, a.get(less));
-                    a.set((($tmp) => less = dart.notNull($tmp) + 1, $tmp)(less), a.get(great));
-                    a.set((($tmp) => great = dart.notNull($tmp) - 1, $tmp)(great), ak);
+                    a.set(((x) => less = dart.notNull(x$) + 1, x$)(less), a.get(great));
+                    a.set(((x) => great = dart.notNull(x$) - 1, x$)(great), ak);
                   } else {
                     a.set(k, a.get(great));
-                    a.set((($tmp) => great = dart.notNull($tmp) - 1, $tmp)(great), ak);
+                    a.set(((x) => great = dart.notNull(x$) - 1, x$)(great), ak);
                   }
                   break;
                 }
@@ -1747,11 +1747,11 @@ var _internal;
                   comp = dart.dinvokef(compare, a.get(great), pivot1);
                   if (dart.notNull(comp) < 0) {
                     a.set(k, a.get(less));
-                    a.set((($tmp) => less = dart.notNull($tmp) + 1, $tmp)(less), a.get(great));
-                    a.set((($tmp) => great = dart.notNull($tmp) - 1, $tmp)(great), ak);
+                    a.set(((x) => less = dart.notNull(x$) + 1, x$)(less), a.get(great));
+                    a.set(((x) => great = dart.notNull(x$) - 1, x$)(great), ak);
                   } else {
                     a.set(k, a.get(great));
-                    a.set((($tmp) => great = dart.notNull($tmp) - 1, $tmp)(great), ak);
+                    a.set(((x) => great = dart.notNull(x$) - 1, x$)(great), ak);
                   }
                   break;
                 }
@@ -1771,8 +1771,8 @@ var _internal;
     Symbol(name) {
       this[_name] = name;
     }
-    Symbol$unvalidated($_name) {
-      this[_name] = $_name;
+    Symbol$unvalidated(name$) {
+      this[_name] = name$;
     }
     Symbol$validated(name) {
       this[_name] = validatePublicSymbol(name);
diff --git a/pkg/dev_compiler/lib/runtime/dart/_isolate_helper.js b/pkg/dev_compiler/lib/runtime/dart/_isolate_helper.js
index 629c83adc6b0..6eff072f8379 100644
--- a/pkg/dev_compiler/lib/runtime/dart/_isolate_helper.js
+++ b/pkg/dev_compiler/lib/runtime/dart/_isolate_helper.js
@@ -22,8 +22,8 @@ var _isolate_helper;
   let _receivePort = Symbol('_receivePort');
   let _id = Symbol('_id');
   class _Serializer extends core.Object {
-    _Serializer(opt$) {
-      let serializeSendPorts = opt$ && 'serializeSendPorts' in opt$ ? opt$.serializeSendPorts : true;
+    _Serializer(opts) {
+      let serializeSendPorts = opts && 'serializeSendPorts' in opts ? opts.serializeSendPorts : true;
       this.serializedObjectIds = new core.Map.identity();
       this[_serializeSendPorts] = dart.as(serializeSendPorts, core.bool);
     }
@@ -157,8 +157,8 @@ var _isolate_helper;
   }
   let _adjustSendPorts = Symbol('_adjustSendPorts');
   class _Deserializer extends core.Object {
-    _Deserializer(opt$) {
-      let adjustSendPorts = opt$ && 'adjustSendPorts' in opt$ ? opt$.adjustSendPorts : true;
+    _Deserializer(opts) {
+      let adjustSendPorts = opts && 'adjustSendPorts' in opts ? opts.adjustSendPorts : true;
       this.deserializedObjects = new core.List();
       this[_adjustSendPorts] = dart.as(adjustSendPorts, core.bool);
     }
@@ -320,8 +320,8 @@ var _isolate_helper;
     }
   }
   // Function _callInIsolate: (_IsolateContext, Function) → dynamic
-  function _callInIsolate(isolate, function) {
-    let result = isolate.eval(function);
+  function _callInIsolate(isolate, function$0) {
+    let result = isolate.eval(function$0);
     exports._globalState.topEventLoop.run();
     return result;
   }
@@ -380,8 +380,8 @@ var _isolate_helper;
   });
   let _nativeDetectEnvironment = Symbol('_nativeDetectEnvironment');
   let _nativeInitWorkerMessageHandler = Symbol('_nativeInitWorkerMessageHandler');
-  let _processWorkerMessage = Symbol('_processWorkerMessage');
-  let _serializePrintMessage = Symbol('_serializePrintMessage');
+  let _processWorkerMessage$ = Symbol('_processWorkerMessage');
+  let _serializePrintMessage$ = Symbol('_serializePrintMessage');
   class _Manager extends core.Object {
     get useWorkers() {
       return this.supportsWorkers;
@@ -417,12 +417,12 @@ var _isolate_helper;
       this.fromCommandLine = !dart.notNull(isWindowDefined) && !dart.notNull(this.isWorker);
     }
     [_nativeInitWorkerMessageHandler]() {
-      let function = function(f, a) {
+      let function$0 = function(f, a) {
         return function(e) {
           f(a, e);
         };
-      }(_foreign_helper.DART_CLOSURE_TO_JS(IsolateNatives[_processWorkerMessage]), this.mainManager);
-      self.onmessage = function;
+      }(_foreign_helper.DART_CLOSURE_TO_JS(IsolateNatives[_processWorkerMessage$]), this.mainManager);
+      self.onmessage = function$0;
       self.dartPrint = self.dartPrint || function(serialize) {
         return function(object) {
           if (self.console && self.console.log) {
@@ -433,7 +433,7 @@ var _isolate_helper;
         };
       }(_foreign_helper.DART_CLOSURE_TO_JS(_serializePrintMessage));
     }
-    static [_serializePrintMessage](object) {
+    static [_serializePrintMessage$](object) {
       return _serializeMessage(dart.map({command: "print", msg: object}));
     }
     maybeCloseWorker() {
@@ -449,7 +449,7 @@ var _isolate_helper;
   let _addRegistration = Symbol('_addRegistration');
   class _IsolateContext extends core.Object {
     _IsolateContext() {
-      this.id = (($tmp) => exports._globalState.nextIsolateId = dart.notNull($tmp) + 1, $tmp).bind(this)(exports._globalState.nextIsolateId);
+      this.id = ((x) => exports._globalState.nextIsolateId = dart.notNull(x$) + 1, x$).bind(this)(exports._globalState.nextIsolateId);
       this.ports = new core.Map();
       this.weakPorts = new core.Set();
       this.isolateStatics = _foreign_helper.JS_CREATE_ISOLATE();
@@ -778,16 +778,16 @@ var _isolate_helper;
       return !!self.postMessage;
     }
   });
-  let _getEventData = Symbol('_getEventData');
-  let _log = Symbol('_log');
-  let _consoleLog = Symbol('_consoleLog');
-  let _getJSFunctionFromName = Symbol('_getJSFunctionFromName');
-  let _getJSFunctionName = Symbol('_getJSFunctionName');
+  let _getEventData$ = Symbol('_getEventData');
+  let _log$ = Symbol('_log');
+  let _consoleLog$ = Symbol('_consoleLog');
+  let _getJSFunctionFromName$ = Symbol('_getJSFunctionFromName');
+  let _getJSFunctionName$ = Symbol('_getJSFunctionName');
   let _allocate = Symbol('_allocate');
-  let _startWorker = Symbol('_startWorker');
-  let _startNonWorker = Symbol('_startNonWorker');
-  let _startIsolate = Symbol('_startIsolate');
-  let _spawnWorker = Symbol('_spawnWorker');
+  let _startWorker$ = Symbol('_startWorker');
+  let _startNonWorker$ = Symbol('_startNonWorker');
+  let _startIsolate$ = Symbol('_startIsolate');
+  let _spawnWorker$ = Symbol('_spawnWorker');
   class IsolateNatives extends core.Object {
     static computeThisScript() {
       let currentScript = _foreign_helper.JS_EMBEDDED_GLOBAL('', _js_embedded_names.CURRENT_SCRIPT);
@@ -833,10 +833,10 @@ var _isolate_helper;
         return matches[1];
       throw new core.UnsupportedError(`Cannot extract URI from "${stack}"`);
     }
-    static [_getEventData](e) {
+    static [_getEventData$](e) {
       return e.data;
     }
-    static [_processWorkerMessage](sender, e) {
+    static [_processWorkerMessage$](sender, e) {
       let msg = _deserializeMessage(_getEventData(e));
       switch (dart.dindex(msg, 'command')) {
         case 'start':
@@ -895,7 +895,7 @@ var _isolate_helper;
         }
       });
     }
-    static [_log](msg) {
+    static [_log$](msg) {
       if (exports._globalState.isWorker) {
         exports._globalState.mainManager.postMessage(_serializeMessage(dart.map({command: 'log', msg: msg})));
       } else {
@@ -908,15 +908,15 @@ var _isolate_helper;
 
       }
     }
-    static [_consoleLog](msg) {
+    static [_consoleLog$](msg) {
       _js_helper.requiresPreamble();
       self.console.log(msg);
     }
-    static [_getJSFunctionFromName](functionName) {
+    static [_getJSFunctionFromName$](functionName) {
       let globalFunctionsContainer = _foreign_helper.JS_EMBEDDED_GLOBAL("", _js_embedded_names.GLOBAL_FUNCTIONS);
       return globalFunctionsContainer[functionName]();
     }
-    static [_getJSFunctionName](f) {
+    static [_getJSFunctionName$](f) {
       return dart.as(dart.is(f, _js_helper.Closure) ? f.$name : null, core.String);
     }
     static [_allocate](ctor) {
@@ -959,7 +959,7 @@ var _isolate_helper;
       }
       return completer.future;
     }
-    static [_startWorker](functionName, uri, args, message, isSpawnUri, startPaused, replyPort, onError) {
+    static [_startWorker$](functionName, uri, args, message, isSpawnUri, startPaused, replyPort, onError) {
       if (args !== null)
         args = new core.List.from(args);
       if (exports._globalState.isWorker) {
@@ -968,7 +968,7 @@ var _isolate_helper;
         _spawnWorker(functionName, uri, args, message, isSpawnUri, startPaused, replyPort, onError);
       }
     }
-    static [_startNonWorker](functionName, uri, args, message, isSpawnUri, startPaused, replyPort) {
+    static [_startNonWorker$](functionName, uri, args, message, isSpawnUri, startPaused, replyPort) {
       if (uri !== null) {
         throw new core.UnsupportedError("Currently spawnUri is not supported without web workers.");
       }
@@ -984,7 +984,7 @@ var _isolate_helper;
       let context = dart.as(_foreign_helper.JS_CURRENT_ISOLATE_CONTEXT(), _IsolateContext);
       return new isolate.Isolate(context.controlPort.sendPort, {pauseCapability: context.pauseCapability, terminateCapability: context.terminateCapability});
     }
-    static [_startIsolate](topLevel, args, message, isSpawnUri, startPaused, replyTo) {
+    static [_startIsolate$](topLevel, args, message, isSpawnUri, startPaused, replyTo) {
       let context = dart.as(_foreign_helper.JS_CURRENT_ISOLATE_CONTEXT(), _IsolateContext);
       _js_helper.Primitives.initializeStatics(context.id);
       replyTo.send(new List.from([_SPAWNED_SIGNAL, context.controlPort.sendPort, context.pauseCapability, context.terminateCapability]));
@@ -1008,7 +1008,7 @@ var _isolate_helper;
         runStartFunction();
       }
     }
-    static [_spawnWorker](functionName, uri, args, message, isSpawnUri, startPaused, replyPort, onError) {
+    static [_spawnWorker$](functionName, uri, args, message, isSpawnUri, startPaused, replyPort, onError) {
       if (uri === null)
         uri = thisScript;
       let worker = new Worker(uri);
@@ -1025,7 +1025,7 @@ var _isolate_helper;
         };
       }(_foreign_helper.DART_CLOSURE_TO_JS(_processWorkerMessage), worker);
       worker.onmessage = processWorkerMessageTrampoline;
-      let workerId = (($tmp) => exports._globalState.nextManagerId = dart.notNull($tmp) + 1, $tmp).bind(this)(exports._globalState.nextManagerId);
+      let workerId = ((x) => exports._globalState.nextManagerId = dart.notNull(x$) + 1, x$).bind(this)(exports._globalState.nextManagerId);
       workerIds.set(worker, workerId);
       exports._globalState.managers.set(workerId, worker);
       worker.postMessage(_serializeMessage(dart.map({command: 'start', id: workerId, replyTo: _serializeMessage(replyPort), args: args, msg: _serializeMessage(message), isSpawnUri: isSpawnUri, startPaused: startPaused, functionName: functionName})));
@@ -1054,8 +1054,8 @@ var _isolate_helper;
   });
   let _checkReplyTo = Symbol('_checkReplyTo');
   class _BaseSendPort extends core.Object {
-    _BaseSendPort($_isolateId) {
-      this[_isolateId] = $_isolateId;
+    _BaseSendPort(isolateId$) {
+      this[_isolateId] = isolateId$;
     }
     [_checkReplyTo](replyTo) {
       if (dart.notNull(replyTo !== null) && dart.notNull(!dart.is(replyTo, _NativeJsSendPort)) && dart.notNull(!dart.is(replyTo, _WorkerSendPort))) {
@@ -1065,8 +1065,8 @@ var _isolate_helper;
   }
   let _isClosed = Symbol('_isClosed');
   class _NativeJsSendPort extends _BaseSendPort {
-    _NativeJsSendPort($_receivePort, isolateId) {
-      this[_receivePort] = $_receivePort;
+    _NativeJsSendPort(receivePort$, isolateId) {
+      this[_receivePort] = receivePort$;
       super._BaseSendPort(isolateId);
     }
     send(message) {
@@ -1094,9 +1094,9 @@ var _isolate_helper;
     }
   }
   class _WorkerSendPort extends _BaseSendPort {
-    _WorkerSendPort($_workerId, isolateId, $_receivePortId) {
-      this[_workerId] = $_workerId;
-      this[_receivePortId] = $_receivePortId;
+    _WorkerSendPort(workerId$, isolateId, receivePortId$) {
+      this[_workerId] = workerId$;
+      this[_receivePortId] = receivePortId$;
       super._BaseSendPort(isolateId);
     }
     send(message) {
@@ -1121,15 +1121,15 @@ var _isolate_helper;
   let _close = Symbol('_close');
   let _add = Symbol('_add');
   class RawReceivePortImpl extends core.Object {
-    RawReceivePortImpl($_handler) {
-      this[_handler] = $_handler;
-      this[_id] = (($tmp) => _nextFreeId = dart.notNull($tmp) + 1, $tmp)(_nextFreeId);
+    RawReceivePortImpl(handler) {
+      this[_handler] = handler;
+      this[_id] = ((x) => _nextFreeId = dart.notNull(x$) + 1, x$)(_nextFreeId);
       this[_isClosed] = false;
       exports._globalState.currentContext.register(this[_id], this);
     }
-    RawReceivePortImpl$weak($_handler) {
-      this[_handler] = $_handler;
-      this[_id] = (($tmp) => _nextFreeId = dart.notNull($tmp) + 1, $tmp)(_nextFreeId);
+    RawReceivePortImpl$weak(handler) {
+      this[_handler] = handler;
+      this[_id] = ((x) => _nextFreeId = dart.notNull(x$) + 1, x$)(_nextFreeId);
       this[_isClosed] = false;
       exports._globalState.currentContext.registerWeak(this[_id], this);
     }
@@ -1173,17 +1173,17 @@ var _isolate_helper;
     ReceivePortImpl$weak() {
       this.ReceivePortImpl$fromRawReceivePort(new RawReceivePortImpl.weak(null));
     }
-    ReceivePortImpl$fromRawReceivePort($_rawPort) {
-      this[_rawPort] = $_rawPort;
+    ReceivePortImpl$fromRawReceivePort(rawPort) {
+      this[_rawPort] = rawPort;
       this[_controller] = null;
       super.Stream();
       this[_controller] = new async.StreamController({onCancel: this.close, sync: true});
       this[_rawPort].handler = this[_controller].add;
     }
-    listen(onData, opt$) {
-      let onError = opt$ && 'onError' in opt$ ? opt$.onError : null;
-      let onDone = opt$ && 'onDone' in opt$ ? opt$.onDone : null;
-      let cancelOnError = opt$ && 'cancelOnError' in opt$ ? opt$.cancelOnError : null;
+    listen(onData, opts) {
+      let onError = opts && 'onError' in opts ? opts.onError : null;
+      let onDone = opts && 'onDone' in opts ? opts.onDone : null;
+      let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : null;
       return this[_controller].stream.listen(onData, {onError: onError, onDone: onDone, cancelOnError: cancelOnError});
     }
     close() {
@@ -1272,8 +1272,8 @@ var _isolate_helper;
     CapabilityImpl() {
       this.CapabilityImpl$_internal(_js_helper.random64());
     }
-    CapabilityImpl$_internal($_id) {
-      this[_id] = $_id;
+    CapabilityImpl$_internal(id) {
+      this[_id] = id;
     }
     get hashCode() {
       let hash = this[_id];
diff --git a/pkg/dev_compiler/lib/runtime/dart/_js_helper.js b/pkg/dev_compiler/lib/runtime/dart/_js_helper.js
index cfb9ee71bee0..b28b726452e7 100644
--- a/pkg/dev_compiler/lib/runtime/dart/_js_helper.js
+++ b/pkg/dev_compiler/lib/runtime/dart/_js_helper.js
@@ -65,10 +65,10 @@ var _js_helper;
   let _fetch = Symbol('_fetch');
   let ConstantStringMap$ = dart.generic(function(K, V) {
     class ConstantStringMap extends ConstantMap$(K, V) {
-      ConstantStringMap$_(length, $_jsObject, $_keys) {
+      ConstantStringMap$_(length, jsObject$, keys$) {
         this.length = length;
-        this[_jsObject] = $_jsObject;
-        this[_keys] = $_keys;
+        this[_jsObject] = jsObject$;
+        this[_keys] = keys$;
         super.ConstantMap$_();
       }
       containsValue(needle) {
@@ -110,8 +110,8 @@ var _js_helper;
   let _protoValue = Symbol('_protoValue');
   let ConstantProtoMap$ = dart.generic(function(K, V) {
     class ConstantProtoMap extends ConstantStringMap$(K, V) {
-      ConstantProtoMap$_(length, jsObject, keys, $_protoValue) {
-        this[_protoValue] = $_protoValue;
+      ConstantProtoMap$_(length, jsObject, keys, protoValue) {
+        this[_protoValue] = protoValue;
         super.ConstantStringMap$_(dart.as(length, core.int), jsObject, dart.as(keys, core.List$(K)));
       }
       containsKey(key) {
@@ -132,8 +132,8 @@ var _js_helper;
   let _map = Symbol('_map');
   let _ConstantMapKeyIterable$ = dart.generic(function(K) {
     class _ConstantMapKeyIterable extends collection.IterableBase$(K) {
-      _ConstantMapKeyIterable($_map) {
-        this[_map] = $_map;
+      _ConstantMapKeyIterable(map$) {
+        this[_map] = map$;
         super.IterableBase();
       }
       get iterator() {
@@ -150,8 +150,8 @@ var _js_helper;
   let _getMap = Symbol('_getMap');
   let GeneralConstantMap$ = dart.generic(function(K, V) {
     class GeneralConstantMap extends ConstantMap$(K, V) {
-      GeneralConstantMap($_jsData) {
-        this[_jsData] = $_jsData;
+      GeneralConstantMap(jsData) {
+        this[_jsData] = jsData;
         super.ConstantMap$_();
       }
       [_getMap]() {
@@ -207,8 +207,8 @@ var _js_helper;
     return object[property];
   }
   // Function callHasOwnProperty: (dynamic, dynamic, String) → bool
-  function callHasOwnProperty(function, object, property) {
-    return function.call(object, property);
+  function callHasOwnProperty(func, object, property) {
+    return func.call(object, property);
   }
   // Function propertySet: (dynamic, String, dynamic) → void
   function propertySet(object, property, value) {
@@ -474,9 +474,9 @@ var _js_helper;
     toString() {
       return `RegExp/${this.pattern}/`;
     }
-    JSSyntaxRegExp(source, opt$) {
-      let multiLine = opt$ && 'multiLine' in opt$ ? opt$.multiLine : false;
-      let caseSensitive = opt$ && 'caseSensitive' in opt$ ? opt$.caseSensitive : true;
+    JSSyntaxRegExp(source, opts) {
+      let multiLine = opts && 'multiLine' in opts ? opts.multiLine : false;
+      let caseSensitive = opts && 'caseSensitive' in opts ? opts.caseSensitive : true;
       this.pattern = source;
       this[_nativeRegExp] = makeNative(source, multiLine, caseSensitive, false);
       this[_nativeGlobalRegExp] = null;
@@ -577,9 +577,9 @@ var _js_helper;
   }
   let _match = Symbol('_match');
   class _MatchImplementation extends core.Object {
-    _MatchImplementation(pattern, $_match) {
+    _MatchImplementation(pattern, match$) {
       this.pattern = pattern;
-      this[_match] = $_match;
+      this[_match] = match$;
       dart.assert(typeof this[_match].input == string);
       dart.assert(typeof this[_match].index == number);
     }
@@ -613,10 +613,10 @@ var _js_helper;
   let _string = Symbol('_string');
   let _start = Symbol('_start');
   class _AllMatchesIterable extends collection.IterableBase$(core.Match) {
-    _AllMatchesIterable($_re, $_string, $_start) {
-      this[_re] = $_re;
-      this[_string] = $_string;
-      this[_start] = $_start;
+    _AllMatchesIterable(re$, string$, start$) {
+      this[_re] = re$;
+      this[_string] = string$;
+      this[_start] = start$;
       super.IterableBase();
     }
     get iterator() {
@@ -627,10 +627,10 @@ var _js_helper;
   let _nextIndex = Symbol('_nextIndex');
   let _current = Symbol('_current');
   class _AllMatchesIterator extends core.Object {
-    _AllMatchesIterator($_regExp, $_string, $_nextIndex) {
-      this[_regExp] = $_regExp;
-      this[_string] = $_string;
-      this[_nextIndex] = $_nextIndex;
+    _AllMatchesIterator(regExp$, string$, nextIndex$) {
+      this[_regExp] = regExp$;
+      this[_string] = string$;
+      this[_nextIndex] = nextIndex$;
       this[_current] = null;
     }
     get current() {
@@ -870,8 +870,8 @@ var _js_helper;
   let _typeName = Symbol('_typeName');
   let _unmangledName = Symbol('_unmangledName');
   class TypeImpl extends core.Object {
-    TypeImpl($_typeName) {
-      this[_typeName] = $_typeName;
+    TypeImpl(typeName$) {
+      this[_typeName] = typeName$;
       this[_unmangledName] = null;
     }
     toString() {
@@ -935,8 +935,8 @@ var _js_helper;
     return _interceptors.getInterceptor(object).constructor.builtin$cls;
   }
   // Function getRuntimeTypeAsString: (dynamic, {onTypeVariable: (int) → String}) → String
-  function getRuntimeTypeAsString(runtimeType, opt$) {
-    let onTypeVariable = opt$ && 'onTypeVariable' in opt$ ? opt$.onTypeVariable : null;
+  function getRuntimeTypeAsString(runtimeType, opts) {
+    let onTypeVariable = opts && 'onTypeVariable' in opts ? opts.onTypeVariable : null;
     dart.assert(isJsArray(runtimeType));
     let className = getConstructorName(getIndex(runtimeType, 0));
     return `${className}` + `${joinArguments(runtimeType, 1, {onTypeVariable: onTypeVariable})}`;
@@ -946,8 +946,8 @@ var _js_helper;
     return type.builtin$cls;
   }
   // Function runtimeTypeToString: (dynamic, {onTypeVariable: (int) → String}) → String
-  function runtimeTypeToString(type, opt$) {
-    let onTypeVariable = opt$ && 'onTypeVariable' in opt$ ? opt$.onTypeVariable : null;
+  function runtimeTypeToString(type, opts) {
+    let onTypeVariable = opts && 'onTypeVariable' in opts ? opts.onTypeVariable : null;
     if (type === null) {
       return 'dynamic';
     } else if (isJsArray(type)) {
@@ -965,8 +965,8 @@ var _js_helper;
     }
   }
   // Function joinArguments: (dynamic, int, {onTypeVariable: (int) → String}) → String
-  function joinArguments(types, startIndex, opt$) {
-    let onTypeVariable = opt$ && 'onTypeVariable' in opt$ ? opt$.onTypeVariable : null;
+  function joinArguments(types, startIndex, opts) {
+    let onTypeVariable = opts && 'onTypeVariable' in opts ? opts.onTypeVariable : null;
     if (types === null)
       return '';
     dart.assert(isJsArray(types));
@@ -1271,14 +1271,14 @@ var _js_helper;
     return areAssignableMaps(sNamedParameters, tNamedParameters);
   }
   // Function invoke: (dynamic, dynamic) → dynamic
-  function invoke(function, arguments) {
-    return invokeOn(function, null, arguments);
+  function invoke(func, arguments) {
+    return invokeOn(func, null, arguments);
   }
   // Function invokeOn: (dynamic, dynamic, dynamic) → Object
-  function invokeOn(function, receiver, arguments) {
-    dart.assert(isJsFunction(function));
+  function invokeOn(func, receiver, arguments) {
+    dart.assert(isJsFunction(func));
     dart.assert(dart.notNull(arguments === null) || dart.notNull(isJsArray(arguments)));
-    return function.apply(receiver, arguments);
+    return func.apply(receiver, arguments);
   }
   // Function call: (dynamic, String) → dynamic
   function call(object, name) {
@@ -1395,12 +1395,12 @@ var _js_helper;
   let _namedIndices = Symbol('_namedIndices');
   let _getCachedInvocation = Symbol('_getCachedInvocation');
   class JSInvocationMirror extends core.Object {
-    JSInvocationMirror($_memberName, $_internalName, $_kind, $_arguments, $_namedArgumentNames) {
-      this[_memberName] = $_memberName;
-      this[_internalName] = $_internalName;
-      this[_kind] = $_kind;
-      this[_arguments] = $_arguments;
-      this[_namedArgumentNames] = $_namedArgumentNames;
+    JSInvocationMirror(memberName$, internalName$, kind$, arguments$, namedArgumentNames) {
+      this[_memberName] = memberName$;
+      this[_internalName] = internalName$;
+      this[_kind] = kind$;
+      this[_arguments] = arguments$;
+      this[_namedArgumentNames] = namedArgumentNames;
       this[_namedIndices] = null;
     }
     get memberName() {
@@ -1670,11 +1670,11 @@ var _js_helper;
           positions.set(this.parameterName(index), index);
         }
         let index = 0;
-        ((_) => {
-          _.sort();
-          return _;
+        ((_$) => {
+          _$.sort();
+          return _$;
         }).bind(this)(positions.keys.toList()).forEach(((name) => {
-          this.cachedSortedIndices.set((($tmp) => index = dart.notNull($tmp) + 1, $tmp)(index), positions.get(name));
+          this.cachedSortedIndices.set(((x) => index = dart.notNull(x$) + 1, x$)(index), positions.get(name));
         }).bind(this));
       }
       return dart.as(this.cachedSortedIndices.get(unsortedIndex), core.int);
@@ -1704,8 +1704,8 @@ var _js_helper;
     let metadata = _foreign_helper.JS_EMBEDDED_GLOBAL('', _js_embedded_names.METADATA);
     return metadata[index];
   }
-  let _throwFormatException = Symbol('_throwFormatException');
-  let _fromCharCodeApply = Symbol('_fromCharCodeApply');
+  let _throwFormatException$ = Symbol('_throwFormatException');
+  let _fromCharCodeApply$ = Symbol('_fromCharCodeApply');
   let _mangledNameMatchesType = Symbol('_mangledNameMatchesType');
   class Primitives extends core.Object {
     static initializeStatics(id) {
@@ -1720,7 +1720,7 @@ var _js_helper;
       }
       return hash;
     }
-    static [_throwFormatException](string) {
+    static [_throwFormatException$](string) {
       throw new core.FormatException(string);
     }
     static parseInt(source, radix, handleError) {
@@ -1845,7 +1845,7 @@ var _js_helper;
       }
       return null;
     }
-    static [_fromCharCodeApply](array) {
+    static [_fromCharCodeApply$](array) {
       let result = "";
       let kMaxApply = 500;
       let end = array.length;
@@ -2007,7 +2007,7 @@ var _js_helper;
       }
       object[key] = value;
     }
-    static functionNoSuchMethod(function, positionalArguments, namedArguments) {
+    static functionNoSuchMethod(func, positionalArguments, namedArguments) {
       let argumentCount = 0;
       let arguments = new List.from([]);
       let namedArgumentList = new List.from([]);
@@ -2025,12 +2025,12 @@ var _js_helper;
         }).bind(this));
       }
       let selectorName = `${_foreign_helper.JS_GET_NAME("CALL_PREFIX")}$${argumentCount}${names}`;
-      return dart.dinvoke(function, 'noSuchMethod', createUnmangledInvocationMirror(dart.throw_("Unimplemented SymbolLiteral: #call"), selectorName, JSInvocationMirror.METHOD, arguments, namedArgumentList));
+      return dart.dinvoke(func, 'noSuchMethod', createUnmangledInvocationMirror(dart.throw_("Unimplemented SymbolLiteral: #call"), selectorName, JSInvocationMirror.METHOD, arguments, namedArgumentList));
     }
-    static applyFunction(function, positionalArguments, namedArguments) {
-      return namedArguments === null ? applyFunctionWithPositionalArguments(function, positionalArguments) : applyFunctionWithNamedArguments(function, positionalArguments, namedArguments);
+    static applyFunction(func, positionalArguments, namedArguments) {
+      return namedArguments === null ? applyFunctionWithPositionalArguments(func, positionalArguments) : applyFunctionWithNamedArguments(func, positionalArguments, namedArguments);
     }
-    static applyFunctionWithPositionalArguments(function, positionalArguments) {
+    static applyFunctionWithPositionalArguments(func, positionalArguments) {
       let argumentCount = 0;
       let arguments = null;
       if (positionalArguments !== null) {
@@ -2044,24 +2044,24 @@ var _js_helper;
         arguments = new List.from([]);
       }
       let selectorName = `${_foreign_helper.JS_GET_NAME("CALL_PREFIX")}$${argumentCount}`;
-      let jsFunction = function[selectorName];
+      let jsFunction = func[selectorName];
       if (jsFunction === null) {
-        return functionNoSuchMethod(function, positionalArguments, null);
+        return functionNoSuchMethod(func, positionalArguments, null);
       }
-      return jsFunction.apply(function, arguments);
+      return jsFunction.apply(func, arguments);
     }
-    static applyFunctionWithNamedArguments(function, positionalArguments, namedArguments) {
+    static applyFunctionWithNamedArguments(func, positionalArguments, namedArguments) {
       if (namedArguments.isEmpty) {
-        return applyFunctionWithPositionalArguments(function, positionalArguments);
+        return applyFunctionWithPositionalArguments(func, positionalArguments);
       }
-      let interceptor = _interceptors.getInterceptor(function);
+      let interceptor = _interceptors.getInterceptor(func);
       let jsFunction = interceptor["call*"];
       if (jsFunction === null) {
-        return functionNoSuchMethod(function, positionalArguments, namedArguments);
+        return functionNoSuchMethod(func, positionalArguments, namedArguments);
       }
       let info = new ReflectionInfo(jsFunction);
       if (dart.notNull(info === null) || !dart.notNull(info.areOptionalParametersNamed)) {
-        return functionNoSuchMethod(function, positionalArguments, namedArguments);
+        return functionNoSuchMethod(func, positionalArguments, namedArguments);
       }
       if (positionalArguments !== null) {
         positionalArguments = new core.List.from(positionalArguments);
@@ -2069,7 +2069,7 @@ var _js_helper;
         positionalArguments = new List.from([]);
       }
       if (info.requiredParameterCount !== positionalArguments.length) {
-        return functionNoSuchMethod(function, positionalArguments, namedArguments);
+        return functionNoSuchMethod(func, positionalArguments, namedArguments);
       }
       let defaultArguments = new core.Map();
       for (let i = 0; dart.notNull(i) < dart.notNull(info.optionalParameterCount); i = dart.notNull(i) + 1) {
@@ -2088,10 +2088,10 @@ var _js_helper;
         }
       }).bind(this));
       if (bad) {
-        return functionNoSuchMethod(function, positionalArguments, namedArguments);
+        return functionNoSuchMethod(func, positionalArguments, namedArguments);
       }
       positionalArguments.addAll(defaultArguments.values);
-      return jsFunction.apply(function, positionalArguments);
+      return jsFunction.apply(func, positionalArguments);
     }
     static [_mangledNameMatchesType](mangledName, type) {
       return mangledName == type[_typeName];
@@ -2214,13 +2214,13 @@ var _js_helper;
   let _receiver = Symbol('_receiver');
   let _pattern = Symbol('_pattern');
   class TypeErrorDecoder extends core.Object {
-    TypeErrorDecoder($_arguments, $_argumentsExpr, $_expr, $_method, $_receiver, $_pattern) {
-      this[_arguments] = $_arguments;
-      this[_argumentsExpr] = $_argumentsExpr;
-      this[_expr] = $_expr;
-      this[_method] = $_method;
-      this[_receiver] = $_receiver;
-      this[_pattern] = $_pattern;
+    TypeErrorDecoder(arguments$, argumentsExpr$, expr$, method$, receiver$, pattern$) {
+      this[_arguments] = arguments$;
+      this[_argumentsExpr] = argumentsExpr$;
+      this[_expr] = expr$;
+      this[_method] = method$;
+      this[_receiver] = receiver$;
+      this[_pattern] = pattern$;
     }
     matchTypeError(message) {
       let match = new RegExp(this[_pattern]).exec(message);
@@ -2274,7 +2274,7 @@ var _js_helper;
       return new TypeErrorDecoder(arguments, argumentsExpr, expr, method, receiver, pattern);
     }
     static provokeCallErrorOn(expression) {
-      let function = function($expr$) {
+      let func = function($expr$) {
         var $argumentsExpr$ = '$arguments$';
         try {
           $expr$.$method$($argumentsExpr$);
@@ -2283,10 +2283,10 @@ var _js_helper;
         }
 
       };
-      return function(expression);
+      return func(expression);
     }
     static provokeCallErrorOnNull() {
-      let function = function() {
+      let func = function() {
         var $argumentsExpr$ = '$arguments$';
         try {
           null.$method$($argumentsExpr$);
@@ -2295,10 +2295,10 @@ var _js_helper;
         }
 
       };
-      return function();
+      return func();
     }
     static provokeCallErrorOnUndefined() {
-      let function = function() {
+      let func = function() {
         var $argumentsExpr$ = '$arguments$';
         try {
           (void 0).$method$($argumentsExpr$);
@@ -2307,10 +2307,10 @@ var _js_helper;
         }
 
       };
-      return function();
+      return func();
     }
     static provokePropertyErrorOn(expression) {
-      let function = function($expr$) {
+      let func = function($expr$) {
         try {
           $expr$.$method$;
         } catch (e) {
@@ -2318,10 +2318,10 @@ var _js_helper;
         }
 
       };
-      return function(expression);
+      return func(expression);
     }
     static provokePropertyErrorOnNull() {
-      let function = function() {
+      let func = function() {
         try {
           null.$method$;
         } catch (e) {
@@ -2329,10 +2329,10 @@ var _js_helper;
         }
 
       };
-      return function();
+      return func();
     }
     static provokePropertyErrorOnUndefined() {
-      let function = function() {
+      let func = function() {
         try {
           (void 0).$method$;
         } catch (e) {
@@ -2340,7 +2340,7 @@ var _js_helper;
         }
 
       };
-      return function();
+      return func();
     }
   }
   dart.defineLazyProperties(TypeErrorDecoder, {
@@ -2377,8 +2377,8 @@ var _js_helper;
   });
   let _message = Symbol('_message');
   class NullError extends core.Error {
-    NullError($_message, match) {
-      this[_message] = $_message;
+    NullError(message$, match) {
+      this[_message] = message$;
       this[_method] = dart.as(match === null ? null : match.method, core.String);
       super.Error();
     }
@@ -2389,8 +2389,8 @@ var _js_helper;
     }
   }
   class JsNoSuchMethodError extends core.Error {
-    JsNoSuchMethodError($_message, match) {
-      this[_message] = $_message;
+    JsNoSuchMethodError(message$, match) {
+      this[_message] = message$;
       this[_method] = dart.as(match === null ? null : match.method, core.String);
       this[_receiver] = dart.as(match === null ? null : match.receiver, core.String);
       super.Error();
@@ -2405,8 +2405,8 @@ var _js_helper;
     }
   }
   class UnknownJsTypeError extends core.Error {
-    UnknownJsTypeError($_message) {
-      this[_message] = $_message;
+    UnknownJsTypeError(message$) {
+      this[_message] = message$;
       super.Error();
     }
     toString() {
@@ -2491,8 +2491,8 @@ var _js_helper;
   let _exception = Symbol('_exception');
   let _trace = Symbol('_trace');
   class _StackTrace extends core.Object {
-    _StackTrace($_exception) {
-      this[_exception] = $_exception;
+    _StackTrace(exception$) {
+      this[_exception] = exception$;
       this[_trace] = null;
     }
     toString() {
@@ -2518,8 +2518,8 @@ var _js_helper;
     let index = 0;
     let length = getLength(keyValuePairs);
     while (dart.notNull(index) < dart.notNull(length)) {
-      let key = getIndex(keyValuePairs, (($tmp) => index = dart.notNull($tmp) + 1, $tmp)(index));
-      let value = getIndex(keyValuePairs, (($tmp) => index = dart.notNull($tmp) + 1, $tmp)(index));
+      let key = getIndex(keyValuePairs, ((x) => index = dart.notNull(x$) + 1, x$)(index));
+      let value = getIndex(keyValuePairs, ((x) => index = dart.notNull(x$) + 1, x$)(index));
       result.set(key, value);
     }
     return result;
@@ -2544,16 +2544,16 @@ var _js_helper;
   function convertDartClosureToJS(closure, arity) {
     if (closure === null)
       return null;
-    let function = closure.$identity;
-    if (!!function)
-      return function;
-    function = function(closure, arity, context, invoke) {
+    let func = closure.$identity;
+    if (!!func)
+      return func;
+    func = function(closure, arity, context, invoke) {
       return function(a1, a2, a3, a4) {
         return invoke(closure, context, arity, a1, a2, a3, a4);
       };
     }(closure, arity, _foreign_helper.JS_CURRENT_ISOLATE_CONTEXT(), _foreign_helper.DART_CLOSURE_TO_JS(invokeClosure));
-    closure.$identity = function;
-    return function;
+    closure.$identity = func;
+    return func;
   }
   class Closure extends core.Object {
     Closure() {
@@ -2563,11 +2563,11 @@ var _js_helper;
         BoundClosure.receiverOf(dart.as(void 0, BoundClosure));
         BoundClosure.selfOf(dart.as(void 0, BoundClosure));
       });
-      let function = functions[0];
-      let name = dart.as(function.$stubName, core.String);
-      let callName = dart.as(function.$callName, core.String);
-      function.$reflectionInfo = reflectionInfo;
-      let info = new ReflectionInfo(function);
+      let func = functions[0];
+      let name = dart.as(func.$stubName, core.String);
+      let callName = dart.as(func.$callName, core.String);
+      func.$reflectionInfo = reflectionInfo;
+      let info = new ReflectionInfo(func);
       let functionType = info.functionType;
       let prototype = isStatic ? Object.create(new TearOffClosure().constructor.prototype) : Object.create(new BoundClosure(null, null, null, null).constructor.prototype);
       prototype.$initialize = prototype.constructor;
@@ -2575,16 +2575,16 @@ var _js_helper;
         this.$initialize();
       } : isCsp ? function(a, b, c, d) {
         this.$initialize(a, b, c, d);
-      } : new Function("a", "b", "c", "d", "this.$initialize(a,b,c,d);" + (($tmp) => functionCounter = dart.notNull($tmp) + 1, $tmp)(functionCounter));
+      } : new Function("a", "b", "c", "d", "this.$initialize(a,b,c,d);" + ((x) => functionCounter = dart.notNull(x$) + 1, x$)(functionCounter));
       prototype.constructor = constructor;
       constructor.prototype = prototype;
-      let trampoline = function;
+      let trampoline = func;
       let isIntercepted = false;
       if (!dart.notNull(isStatic)) {
         if (jsArguments.length == 1) {
           isIntercepted = true;
         }
-        trampoline = forwardCallTo(receiver, function, isIntercepted);
+        trampoline = forwardCallTo(receiver, func, isIntercepted);
         trampoline.$reflectionInfo = reflectionInfo;
       } else {
         prototype.$name = propertyName;
@@ -2619,7 +2619,7 @@ var _js_helper;
       prototype["call*"] = trampoline;
       return constructor;
     }
-    static cspForwardCall(arity, isSuperCall, stubName, function) {
+    static cspForwardCall(arity, isSuperCall, stubName, func) {
       let getSelf = _foreign_helper.RAW_DART_FUNCTION_REF(BoundClosure.selfOf);
       if (isSuperCall)
         arity = -1;
@@ -2665,30 +2665,30 @@ var _js_helper;
             return function() {
               return f.apply(s(this), arguments);
             };
-          }(function, getSelf);
+          }(func, getSelf);
       }
     }
     static get isCsp() {
       return typeof dart_precompiled == "function";
     }
-    static forwardCallTo(receiver, function, isIntercepted) {
+    static forwardCallTo(receiver, func, isIntercepted) {
       if (isIntercepted)
-        return forwardInterceptedCallTo(receiver, function);
-      let stubName = dart.as(function.$stubName, core.String);
-      let arity = function.length;
+        return forwardInterceptedCallTo(receiver, func);
+      let stubName = dart.as(func.$stubName, core.String);
+      let arity = func.length;
       let lookedUpFunction = receiver[stubName];
-      let isSuperCall = !dart.notNull(core.identical(function, lookedUpFunction));
+      let isSuperCall = !dart.notNull(core.identical(func, lookedUpFunction));
       if (dart.notNull(isCsp) || dart.notNull(isSuperCall) || dart.notNull(arity) >= 27) {
-        return cspForwardCall(arity, isSuperCall, stubName, function);
+        return cspForwardCall(arity, isSuperCall, stubName, func);
       }
       if (arity === 0) {
-        return new Function('return function(){' + `return this.${BoundClosure.selfFieldName()}.${stubName}();` + `${(($tmp) => functionCounter = dart.notNull($tmp) + 1, $tmp)(functionCounter)}` + '}')();
+        return new Function('return function(){' + `return this.${BoundClosure.selfFieldName()}.${stubName}();` + `${((x) => functionCounter = dart.notNull(x$) + 1, x$)(functionCounter)}` + '}')();
       }
       dart.assert(1 <= dart.notNull(arity) && dart.notNull(arity) < 27);
       let arguments = "abcdefghijklmnopqrstuvwxyz".split("").splice(0, arity).join(",");
-      return new Function(`return function(${arguments}){` + `return this.${BoundClosure.selfFieldName()}.${stubName}(${arguments});` + `${(($tmp) => functionCounter = dart.notNull($tmp) + 1, $tmp)(functionCounter)}` + '}')();
+      return new Function(`return function(${arguments}){` + `return this.${BoundClosure.selfFieldName()}.${stubName}(${arguments});` + `${((x) => functionCounter = dart.notNull(x$) + 1, x$)(functionCounter)}` + '}')();
     }
-    static cspForwardInterceptedCall(arity, isSuperCall, name, function) {
+    static cspForwardInterceptedCall(arity, isSuperCall, name, func) {
       let getSelf = _foreign_helper.RAW_DART_FUNCTION_REF(BoundClosure.selfOf);
       let getReceiver = _foreign_helper.RAW_DART_FUNCTION_REF(BoundClosure.receiverOf);
       if (isSuperCall)
@@ -2739,26 +2739,26 @@ var _js_helper;
               Array.prototype.push.apply(a, arguments);
               return f.apply(s(this), a);
             };
-          }(function, getSelf, getReceiver);
+          }(func, getSelf, getReceiver);
       }
     }
-    static forwardInterceptedCallTo(receiver, function) {
+    static forwardInterceptedCallTo(receiver, func) {
       let selfField = BoundClosure.selfFieldName();
       let receiverField = BoundClosure.receiverFieldName();
-      let stubName = dart.as(function.$stubName, core.String);
-      let arity = function.length;
+      let stubName = dart.as(func.$stubName, core.String);
+      let arity = func.length;
       let isCsp = typeof dart_precompiled == "function";
       let lookedUpFunction = receiver[stubName];
-      let isSuperCall = !dart.notNull(core.identical(function, lookedUpFunction));
+      let isSuperCall = !dart.notNull(core.identical(func, lookedUpFunction));
       if (dart.notNull(isCsp) || dart.notNull(isSuperCall) || dart.notNull(arity) >= 28) {
-        return cspForwardInterceptedCall(arity, isSuperCall, stubName, function);
+        return cspForwardInterceptedCall(arity, isSuperCall, stubName, func);
       }
       if (arity === 1) {
-        return new Function('return function(){' + `return this.${selfField}.${stubName}(this.${receiverField});` + `${(($tmp) => functionCounter = dart.notNull($tmp) + 1, $tmp)(functionCounter)}` + '}')();
+        return new Function('return function(){' + `return this.${selfField}.${stubName}(this.${receiverField});` + `${((x) => functionCounter = dart.notNull(x$) + 1, x$)(functionCounter)}` + '}')();
       }
       dart.assert(1 < dart.notNull(arity) && dart.notNull(arity) < 28);
       let arguments = "abcdefghijklmnopqrstuvwxyz".split("").splice(0, dart.notNull(arity) - 1).join(",");
-      return new Function(`return function(${arguments}){` + `return this.${selfField}.${stubName}(this.${receiverField}, ${arguments});` + `${(($tmp) => functionCounter = dart.notNull($tmp) + 1, $tmp)(functionCounter)}` + '}')();
+      return new Function(`return function(${arguments}){` + `return this.${selfField}.${stubName}(this.${receiverField}, ${arguments});` + `${((x) => functionCounter = dart.notNull(x$) + 1, x$)(functionCounter)}` + '}')();
     }
     toString() {
       return "Closure";
@@ -2781,11 +2781,11 @@ var _js_helper;
   let _target = Symbol('_target');
   let _name = Symbol('_name');
   class BoundClosure extends TearOffClosure {
-    BoundClosure($_self, $_target, $_receiver, $_name) {
-      this[_self] = $_self;
-      this[_target] = $_target;
-      this[_receiver] = $_receiver;
-      this[_name] = $_name;
+    BoundClosure(self$, target$, receiver$, name$) {
+      this[_self] = self$;
+      this[_target] = target$;
+      this[_receiver] = receiver$;
+      this[_name] = name$;
       super.TearOffClosure();
     }
     ['=='](other) {
@@ -3487,8 +3487,8 @@ var _js_helper;
   let _namedArguments = Symbol('_namedArguments');
   let _convert = Symbol('_convert');
   class FunctionTypeInfoDecoderRing extends core.Object {
-    FunctionTypeInfoDecoderRing($_typeData) {
-      this[_typeData] = $_typeData;
+    FunctionTypeInfoDecoderRing(typeData) {
+      this[_typeData] = typeData;
       this[_cachedToString] = null;
     }
     get [_hasReturnType]() {
@@ -3498,7 +3498,7 @@ var _js_helper;
       return this[_typeData].ret;
     }
     get [_isVoid]() {
-      return !!this[_typeData]["void"];
+      return !!this[_typeData].void;
     }
     get [_hasArguments]() {
       return "args" in this[_typeData];
@@ -3576,8 +3576,8 @@ var _js_helper;
     }
   }
   class UnimplementedNoSuchMethodError extends core.Error {
-    UnimplementedNoSuchMethodError($_message) {
-      this[_message] = $_message;
+    UnimplementedNoSuchMethodError(message$) {
+      this[_message] = message$;
       super.Error();
     }
     toString() {
@@ -3708,8 +3708,8 @@ var _js_helper;
     }));
   }
   class MainError extends core.Error {
-    MainError($_message) {
-      this[_message] = $_message;
+    MainError(message$) {
+      this[_message] = message$;
       super.Error();
     }
     toString() {
diff --git a/pkg/dev_compiler/lib/runtime/dart/_native_typed_data.js b/pkg/dev_compiler/lib/runtime/dart/_native_typed_data.js
index e5df8f851541..6461e1bc336c 100644
--- a/pkg/dev_compiler/lib/runtime/dart/_native_typed_data.js
+++ b/pkg/dev_compiler/lib/runtime/dart/_native_typed_data.js
@@ -125,8 +125,8 @@ var _native_typed_data;
     NativeFloat32x4List(length) {
       this[_storage] = new NativeFloat32List(dart.notNull(length) * 4);
     }
-    NativeFloat32x4List$_externalStorage($_storage) {
-      this[_storage] = $_storage;
+    NativeFloat32x4List$_externalStorage(storage$) {
+      this[_storage] = storage$;
     }
     NativeFloat32x4List$_slowFromList(list) {
       this[_storage] = new NativeFloat32List(dart.notNull(list.length) * 4);
@@ -307,8 +307,8 @@ var _native_typed_data;
     NativeFloat64x2List(length) {
       this[_storage] = new NativeFloat64List(dart.notNull(length) * 2);
     }
-    NativeFloat64x2List$_externalStorage($_storage) {
-      this[_storage] = $_storage;
+    NativeFloat64x2List$_externalStorage(storage$) {
+      this[_storage] = storage$;
     }
     NativeFloat64x2List$_slowFromList(list) {
       this[_storage] = new NativeFloat64List(dart.notNull(list.length) * 2);
@@ -463,9 +463,9 @@ var _native_typed_data;
   let _setInt32 = Symbol('_setInt32');
   let _setUint16 = Symbol('_setUint16');
   let _setUint32 = Symbol('_setUint32');
-  let _create1 = Symbol('_create1');
-  let _create2 = Symbol('_create2');
-  let _create3 = Symbol('_create3');
+  let _create1$ = Symbol('_create1');
+  let _create2$ = Symbol('_create2');
+  let _create3$ = Symbol('_create3');
   class NativeByteData extends NativeTypedData {
     NativeByteData(length) {
       return _create1(_checkLength(length));
@@ -560,13 +560,13 @@ var _native_typed_data;
         endian = typed_data.Endianness.BIG_ENDIAN;
       throw new core.UnsupportedError('Uint64 accessor not supported by dart2js.');
     }
-    static [_create1](arg) {
+    static [_create1$](arg) {
       return dart.as(new DataView(new ArrayBuffer(arg)), NativeByteData);
     }
-    static [_create2](arg1, arg2) {
+    static [_create2$](arg1, arg2) {
       return dart.as(new DataView(arg1, arg2), NativeByteData);
     }
-    static [_create3](arg1, arg2, arg3) {
+    static [_create3$](arg1, arg2, arg3) {
       return dart.as(new DataView(arg1, arg2, arg3), NativeByteData);
     }
   }
@@ -650,13 +650,13 @@ var _native_typed_data;
       let source = this.subarray(start, end);
       return _create1(source);
     }
-    static [_create1](arg) {
+    static [_create1$](arg) {
       return dart.as(new Float32Array(arg), NativeFloat32List);
     }
-    static [_create2](arg1, arg2) {
+    static [_create2$](arg1, arg2) {
       return dart.as(new Float32Array(arg1, arg2), NativeFloat32List);
     }
-    static [_create3](arg1, arg2, arg3) {
+    static [_create3$](arg1, arg2, arg3) {
       return dart.as(new Float32Array(arg1, arg2, arg3), NativeFloat32List);
     }
   }
@@ -683,13 +683,13 @@ var _native_typed_data;
       let source = this.subarray(start, end);
       return _create1(source);
     }
-    static [_create1](arg) {
+    static [_create1$](arg) {
       return dart.as(new Float64Array(arg), NativeFloat64List);
     }
-    static [_create2](arg1, arg2) {
+    static [_create2$](arg1, arg2) {
       return dart.as(new Float64Array(arg1, arg2), NativeFloat64List);
     }
-    static [_create3](arg1, arg2, arg3) {
+    static [_create3$](arg1, arg2, arg3) {
       return dart.as(new Float64Array(arg1, arg2, arg3), NativeFloat64List);
     }
   }
@@ -720,13 +720,13 @@ var _native_typed_data;
       let source = this.subarray(start, end);
       return _create1(source);
     }
-    static [_create1](arg) {
+    static [_create1$](arg) {
       return dart.as(new Int16Array(arg), NativeInt16List);
     }
-    static [_create2](arg1, arg2) {
+    static [_create2$](arg1, arg2) {
       return dart.as(new Int16Array(arg1, arg2), NativeInt16List);
     }
-    static [_create3](arg1, arg2, arg3) {
+    static [_create3$](arg1, arg2, arg3) {
       return dart.as(new Int16Array(arg1, arg2, arg3), NativeInt16List);
     }
   }
@@ -757,13 +757,13 @@ var _native_typed_data;
       let source = this.subarray(start, end);
       return _create1(source);
     }
-    static [_create1](arg) {
+    static [_create1$](arg) {
       return dart.as(new Int32Array(arg), NativeInt32List);
     }
-    static [_create2](arg1, arg2) {
+    static [_create2$](arg1, arg2) {
       return dart.as(new Int32Array(arg1, arg2), NativeInt32List);
     }
-    static [_create3](arg1, arg2, arg3) {
+    static [_create3$](arg1, arg2, arg3) {
       return dart.as(new Int32Array(arg1, arg2, arg3), NativeInt32List);
     }
   }
@@ -794,13 +794,13 @@ var _native_typed_data;
       let source = this.subarray(start, end);
       return _create1(source);
     }
-    static [_create1](arg) {
+    static [_create1$](arg) {
       return dart.as(new Int8Array(arg), NativeInt8List);
     }
-    static [_create2](arg1, arg2) {
+    static [_create2$](arg1, arg2) {
       return dart.as(new Int8Array(arg1, arg2), NativeInt8List);
     }
-    static [_create3](arg1, arg2, arg3) {
+    static [_create3$](arg1, arg2, arg3) {
       return dart.as(new Int8Array(arg1, arg2, arg3), typed_data.Int8List);
     }
   }
@@ -831,13 +831,13 @@ var _native_typed_data;
       let source = this.subarray(start, end);
       return _create1(source);
     }
-    static [_create1](arg) {
+    static [_create1$](arg) {
       return dart.as(new Uint16Array(arg), NativeUint16List);
     }
-    static [_create2](arg1, arg2) {
+    static [_create2$](arg1, arg2) {
       return dart.as(new Uint16Array(arg1, arg2), NativeUint16List);
     }
-    static [_create3](arg1, arg2, arg3) {
+    static [_create3$](arg1, arg2, arg3) {
       return dart.as(new Uint16Array(arg1, arg2, arg3), NativeUint16List);
     }
   }
@@ -868,13 +868,13 @@ var _native_typed_data;
       let source = this.subarray(start, end);
       return _create1(source);
     }
-    static [_create1](arg) {
+    static [_create1$](arg) {
       return dart.as(new Uint32Array(arg), NativeUint32List);
     }
-    static [_create2](arg1, arg2) {
+    static [_create2$](arg1, arg2) {
       return dart.as(new Uint32Array(arg1, arg2), NativeUint32List);
     }
-    static [_create3](arg1, arg2, arg3) {
+    static [_create3$](arg1, arg2, arg3) {
       return dart.as(new Uint32Array(arg1, arg2, arg3), NativeUint32List);
     }
   }
@@ -908,13 +908,13 @@ var _native_typed_data;
       let source = this.subarray(start, end);
       return _create1(source);
     }
-    static [_create1](arg) {
+    static [_create1$](arg) {
       return dart.as(new Uint8ClampedArray(arg), NativeUint8ClampedList);
     }
-    static [_create2](arg1, arg2) {
+    static [_create2$](arg1, arg2) {
       return dart.as(new Uint8ClampedArray(arg1, arg2), NativeUint8ClampedList);
     }
-    static [_create3](arg1, arg2, arg3) {
+    static [_create3$](arg1, arg2, arg3) {
       return dart.as(new Uint8ClampedArray(arg1, arg2, arg3), NativeUint8ClampedList);
     }
   }
@@ -948,21 +948,21 @@ var _native_typed_data;
       let source = this.subarray(start, end);
       return _create1(source);
     }
-    static [_create1](arg) {
+    static [_create1$](arg) {
       return dart.as(new Uint8Array(arg), NativeUint8List);
     }
-    static [_create2](arg1, arg2) {
+    static [_create2$](arg1, arg2) {
       return dart.as(new Uint8Array(arg1, arg2), NativeUint8List);
     }
-    static [_create3](arg1, arg2, arg3) {
+    static [_create3$](arg1, arg2, arg3) {
       return dart.as(new Uint8Array(arg1, arg2, arg3), NativeUint8List);
     }
   }
   dart.defineNamedConstructor(NativeUint8List, 'fromList');
   dart.defineNamedConstructor(NativeUint8List, 'view');
-  let _truncate = Symbol('_truncate');
+  let _truncate$ = Symbol('_truncate');
   class NativeFloat32x4 extends core.Object {
-    static [_truncate](x) {
+    static [_truncate$](x) {
       _list.set(0, dart.as(x, core.num));
       return _list.get(0);
     }
@@ -1228,10 +1228,10 @@ var _native_typed_data;
       return _list.buffer.asUint32List();
     }
   });
-  let _list = Symbol('_list');
-  let _uint32view = Symbol('_uint32view');
+  let _list$ = Symbol('_list');
+  let _uint32view$ = Symbol('_uint32view');
   class NativeInt32x4 extends core.Object {
-    static [_truncate](x) {
+    static [_truncate$](x) {
       _list.set(0, dart.as(x, core.int));
       return _list.get(0);
     }
@@ -1256,7 +1256,7 @@ var _native_typed_data;
       this.w = w ? -1 : 0;
     }
     NativeInt32x4$fromFloat32x4Bits(f) {
-      let floatList = NativeFloat32x4[_list];
+      let floatList = NativeFloat32x4[_list$];
       floatList.set(0, f.x);
       floatList.set(1, f.y);
       floatList.set(2, f.z);
@@ -1375,8 +1375,8 @@ var _native_typed_data;
       return new NativeInt32x4._truncated(this.x, this.y, this.z, _w);
     }
     select(trueValue, falseValue) {
-      let floatList = NativeFloat32x4[_list];
-      let intView = NativeFloat32x4[_uint32view];
+      let floatList = NativeFloat32x4[_list$];
+      let intView = NativeFloat32x4[_uint32view$];
       floatList.set(0, trueValue.x);
       floatList.set(1, trueValue.y);
       floatList.set(2, trueValue.z);
diff --git a/pkg/dev_compiler/lib/runtime/dart/async.js b/pkg/dev_compiler/lib/runtime/dart/async.js
index d9f9e56e7e1d..0647976dbbf3 100644
--- a/pkg/dev_compiler/lib/runtime/dart/async.js
+++ b/pkg/dev_compiler/lib/runtime/dart/async.js
@@ -17,7 +17,7 @@ var async;
       return zone.registerUnaryCallback(dart.as(errorHandler, dart.throw_("Unimplemented type (dynamic) → dynamic")));
     }
   }
-  let _getBestStackTrace = Symbol('_getBestStackTrace');
+  let _getBestStackTrace$ = Symbol('_getBestStackTrace');
   class AsyncError extends core.Object {
     AsyncError(error, stackTrace) {
       this.error = error;
@@ -31,7 +31,7 @@ var async;
     _UncaughtAsyncError(error, stackTrace) {
       super.AsyncError(error, _getBestStackTrace(error, stackTrace));
     }
-    static [_getBestStackTrace](error, stackTrace) {
+    static [_getBestStackTrace$](error, stackTrace) {
       if (stackTrace !== null)
         return stackTrace;
       if (dart.is(error, core.Error)) {
@@ -84,7 +84,7 @@ var async;
         // Function sendEvent: () → void
         function sendEvent() {
           watch.reset();
-          let data = computation((($tmp) => computationCount = dart.notNull($tmp) + 1, $tmp)(computationCount));
+          let data = computation(((x) => computationCount = dart.notNull(x$) + 1, x$)(computationCount));
           controller.add(data);
         }
         // Function startPeriodicTimer: () → void
@@ -123,9 +123,9 @@ var async;
       get isBroadcast() {
         return false;
       }
-      asBroadcastStream(opt$) {
-        let onListen = opt$ && 'onListen' in opt$ ? opt$.onListen : null;
-        let onCancel = opt$ && 'onCancel' in opt$ ? opt$.onCancel : null;
+      asBroadcastStream(opts) {
+        let onListen = opts && 'onListen' in opts ? opts.onListen : null;
+        let onCancel = opts && 'onCancel' in opts ? opts.onCancel : null;
         return new _AsBroadcastStream(this, dart.closureWrap(onListen, "(StreamSubscription<dynamic>) → void"), dart.closureWrap(onCancel, "(StreamSubscription<dynamic>) → void"));
       }
       where(test) {
@@ -214,8 +214,8 @@ var async;
         }
         return controller.stream;
       }
-      handleError(onError, opt$) {
-        let test = opt$ && 'test' in opt$ ? opt$.test : null;
+      handleError(onError, opts) {
+        let test = opts && 'test' in opts ? opts.test : null;
         return new _HandleErrorStream(this, onError, test);
       }
       expand(convert) {
@@ -488,8 +488,8 @@ var async;
           }).bind(this), cancelOnError: true});
         return future;
       }
-      firstWhere(test, opt$) {
-        let defaultValue = opt$ && 'defaultValue' in opt$ ? opt$.defaultValue : null;
+      firstWhere(test, opts) {
+        let defaultValue = opts && 'defaultValue' in opts ? opts.defaultValue : null;
         let future = new _Future();
         let subscription = null;
         subscription = this.listen((value) => {
@@ -513,8 +513,8 @@ var async;
           }).bind(this), cancelOnError: true});
         return future;
       }
-      lastWhere(test, opt$) {
-        let defaultValue = opt$ && 'defaultValue' in opt$ ? opt$.defaultValue : null;
+      lastWhere(test, opts) {
+        let defaultValue = opts && 'defaultValue' in opts ? opts.defaultValue : null;
         let future = new _Future();
         let result = null;
         let foundResult = false;
@@ -599,8 +599,8 @@ var async;
           }).bind(this), cancelOnError: true});
         return future;
       }
-      timeout(timeLimit, opt$) {
-        let onTimeout = opt$ && 'onTimeout' in opt$ ? opt$.onTimeout : null;
+      timeout(timeLimit, opts) {
+        let onTimeout = opts && 'onTimeout' in opts ? opts.onTimeout : null;
         let controller = null;
         let subscription = null;
         let timer = null;
@@ -670,10 +670,10 @@ var async;
   let Stream = Stream$(dart.dynamic);
   let _StreamImpl$ = dart.generic(function(T) {
     class _StreamImpl extends Stream$(T) {
-      listen(onData, opt$) {
-        let onError = opt$ && 'onError' in opt$ ? opt$.onError : null;
-        let onDone = opt$ && 'onDone' in opt$ ? opt$.onDone : null;
-        let cancelOnError = opt$ && 'cancelOnError' in opt$ ? opt$.cancelOnError : null;
+      listen(onData, opts) {
+        let onError = opts && 'onError' in opts ? opts.onError : null;
+        let onDone = opts && 'onDone' in opts ? opts.onDone : null;
+        let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : null;
         cancelOnError = core.identical(true, cancelOnError);
         let subscription = this[_createSubscription](onData, onError, onDone, cancelOnError);
         this[_onListen](subscription);
@@ -689,8 +689,8 @@ var async;
   let _StreamImpl = _StreamImpl$(dart.dynamic);
   let _ControllerStream$ = dart.generic(function(T) {
     class _ControllerStream extends _StreamImpl$(T) {
-      _ControllerStream($_controller) {
-        this[_controller] = $_controller;
+      _ControllerStream(controller$) {
+        this[_controller] = controller$;
         super._StreamImpl();
       }
       [_createSubscription](onData, onError, onDone, cancelOnError) {
@@ -1080,8 +1080,8 @@ var async;
   let _BufferingStreamSubscription = _BufferingStreamSubscription$(dart.dynamic);
   let _ControllerSubscription$ = dart.generic(function(T) {
     class _ControllerSubscription extends _BufferingStreamSubscription$(T) {
-      _ControllerSubscription($_controller, onData, onError, onDone, cancelOnError) {
-        this[_controller] = $_controller;
+      _ControllerSubscription(controller$, onData, onError, onDone, cancelOnError) {
+        this[_controller] = controller$;
         super._BufferingStreamSubscription(onData, onError, onDone, cancelOnError);
       }
       [_onCancel]() {
@@ -1154,9 +1154,9 @@ var async;
   let _mayComplete = Symbol('_mayComplete');
   let _BroadcastStreamController$ = dart.generic(function(T) {
     class _BroadcastStreamController extends core.Object {
-      _BroadcastStreamController($_onListen, $_onCancel) {
-        this[_onListen] = $_onListen;
-        this[_onCancel] = $_onCancel;
+      _BroadcastStreamController(onListen$, onCancel$) {
+        this[_onListen] = onListen$;
+        this[_onCancel] = onCancel$;
         this[_state] = _BroadcastStreamController._STATE_INITIAL;
         this[_next] = null;
         this[_previous] = null;
@@ -1287,8 +1287,8 @@ var async;
       get done() {
         return this[_ensureDoneFuture]();
       }
-      addStream(stream, opt$) {
-        let cancelOnError = opt$ && 'cancelOnError' in opt$ ? opt$.cancelOnError : true;
+      addStream(stream, opts) {
+        let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : true;
         if (!dart.notNull(this[_mayAddEvent]))
           throw this[_addEventError]();
         this[_state] = _BroadcastStreamController._STATE_ADDSTREAM;
@@ -1532,8 +1532,8 @@ var async;
   });
   let _DoneSubscription = _DoneSubscription$(dart.dynamic);
   class DeferredLibrary extends core.Object {
-    DeferredLibrary(libraryName, opt$) {
-      let uri = opt$ && 'uri' in opt$ ? opt$.uri : null;
+    DeferredLibrary(libraryName, opts) {
+      let uri = opts && 'uri' in opts ? opts.uri : null;
       this.libraryName = libraryName;
       this.uri = uri;
     }
@@ -1543,8 +1543,8 @@ var async;
   }
   let _s = Symbol('_s');
   class DeferredLoadException extends core.Object {
-    DeferredLoadException($_s) {
-      this[_s] = $_s;
+    DeferredLoadException(s$) {
+      this[_s] = s$;
     }
     toString() {
       return `DeferredLoadException: '${this[_s]}'`;
@@ -1621,9 +1621,9 @@ var async;
         }).bind(this));
         return dart.as(result, Future$(T));
       }
-      static wait(futures, opt$) {
-        let eagerError = opt$ && 'eagerError' in opt$ ? opt$.eagerError : false;
-        let cleanUp = opt$ && 'cleanUp' in opt$ ? opt$.cleanUp : null;
+      static wait(futures, opts) {
+        let eagerError = opts && 'eagerError' in opts ? opts.eagerError : false;
+        let cleanUp = opts && 'cleanUp' in opts ? opts.cleanUp : null;
         let result = new _Future();
         let values = null;
         let remaining = 0;
@@ -1654,7 +1654,7 @@ var async;
           }
         }
         for (let future of futures) {
-          let pos = (($tmp) => remaining = dart.notNull($tmp) + 1, $tmp)(remaining);
+          let pos = ((x) => remaining = dart.notNull(x$) + 1, x$)(remaining);
           future.then(((value) => {
             remaining = dart.notNull(remaining) - 1;
             if (values !== null) {
@@ -1906,10 +1906,10 @@ var async;
   let _setErrorObject = Symbol('_setErrorObject');
   let _setError = Symbol('_setError');
   let _removeListeners = Symbol('_removeListeners');
-  let _chainForeignFuture = Symbol('_chainForeignFuture');
-  let _chainCoreFuture = Symbol('_chainCoreFuture');
+  let _chainForeignFuture$ = Symbol('_chainForeignFuture');
+  let _chainCoreFuture$ = Symbol('_chainCoreFuture');
   let _completeWithValue = Symbol('_completeWithValue');
-  let _propagateToListeners = Symbol('_propagateToListeners');
+  let _propagateToListeners$ = Symbol('_propagateToListeners');
   let _Future$ = dart.generic(function(T) {
     class _Future extends core.Object {
       _Future() {
@@ -1955,8 +1955,8 @@ var async;
           this[_state] = _Future._INCOMPLETE;
         }
       }
-      then(f, opt$) {
-        let onError = opt$ && 'onError' in opt$ ? opt$.onError : null;
+      then(f, opts) {
+        let onError = opts && 'onError' in opts ? opts.onError : null;
         let result = new _Future();
         if (!dart.notNull(core.identical(result[_zone], _ROOT_ZONE))) {
           f = dart.closureWrap(result[_zone].registerUnaryCallback(f), "(T) → dynamic");
@@ -1967,8 +1967,8 @@ var async;
         this[_addListener](new _FutureListener.then(result, f, onError));
         return result;
       }
-      catchError(onError, opt$) {
-        let test = opt$ && 'test' in opt$ ? opt$.test : null;
+      catchError(onError, opts) {
+        let test = opts && 'test' in opts ? opts.test : null;
         let result = new _Future();
         if (!dart.notNull(core.identical(result[_zone], _ROOT_ZONE))) {
           onError = _registerErrorHandler(onError, result[_zone]);
@@ -2039,7 +2039,7 @@ var async;
         }
         return prev;
       }
-      static [_chainForeignFuture](source, target) {
+      static [_chainForeignFuture$](source, target) {
         dart.assert(!dart.notNull(target[_isComplete]));
         dart.assert(!dart.is(source, _Future));
         target[_isChained] = true;
@@ -2053,7 +2053,7 @@ var async;
             target._completeError(error, dart.as(stackTrace, core.StackTrace));
           }).bind(this)});
       }
-      static [_chainCoreFuture](source, target) {
+      static [_chainCoreFuture$](source, target) {
         dart.assert(!dart.notNull(target[_isComplete]));
         dart.assert(dart.is(source, _Future));
         target[_isChained] = true;
@@ -2127,7 +2127,7 @@ var async;
           this[_completeError](error, stackTrace);
         }).bind(this));
       }
-      static [_propagateToListeners](source, listeners) {
+      static [_propagateToListeners$](source, listeners) {
         while (true) {
           dart.assert(source[_isComplete]);
           let hasError = source[_hasError];
@@ -2287,8 +2287,8 @@ var async;
           source = result;
         }
       }
-      timeout(timeLimit, opt$) {
-        let onTimeout = opt$ && 'onTimeout' in opt$ ? opt$.onTimeout : null;
+      timeout(timeLimit, opts) {
+        let onTimeout = opts && 'onTimeout' in opts ? opts.onTimeout : null;
         if (this[_isComplete])
           return new _Future.immediate(this);
         let result = new _Future();
@@ -2407,15 +2407,15 @@ var async;
     Zone.current.scheduleMicrotask(Zone.current.bindCallback(callback, {runGuarded: true}));
   }
   let _scheduleImmediate = Symbol('_scheduleImmediate');
-  let _initializeScheduleImmediate = Symbol('_initializeScheduleImmediate');
-  let _scheduleImmediateJsOverride = Symbol('_scheduleImmediateJsOverride');
-  let _scheduleImmediateWithSetImmediate = Symbol('_scheduleImmediateWithSetImmediate');
-  let _scheduleImmediateWithTimer = Symbol('_scheduleImmediateWithTimer');
+  let _initializeScheduleImmediate$ = Symbol('_initializeScheduleImmediate');
+  let _scheduleImmediateJsOverride$ = Symbol('_scheduleImmediateJsOverride');
+  let _scheduleImmediateWithSetImmediate$ = Symbol('_scheduleImmediateWithSetImmediate');
+  let _scheduleImmediateWithTimer$ = Symbol('_scheduleImmediateWithTimer');
   class _AsyncRun extends core.Object {
     static [_scheduleImmediate](callback) {
       dart.dinvokef(scheduleImmediateClosure, callback);
     }
-    static [_initializeScheduleImmediate]() {
+    static [_initializeScheduleImmediate$]() {
       _js_helper.requiresPreamble();
       if (self.scheduleImmediate !== null) {
         return _scheduleImmediateJsOverride;
@@ -2445,7 +2445,7 @@ var async;
       }
       return _scheduleImmediateWithTimer;
     }
-    static [_scheduleImmediateJsOverride](callback) {
+    static [_scheduleImmediateJsOverride$](callback) {
       // Function internalCallback: () → dynamic
       function internalCallback() {
         _isolate_helper.leaveJsAsync();
@@ -2455,7 +2455,7 @@ var async;
       _isolate_helper.enterJsAsync();
       self.scheduleImmediate(_js_helper.convertDartClosureToJS(internalCallback, 0));
     }
-    static [_scheduleImmediateWithSetImmediate](callback) {
+    static [_scheduleImmediateWithSetImmediate$](callback) {
       // Function internalCallback: () → dynamic
       function internalCallback() {
         _isolate_helper.leaveJsAsync();
@@ -2465,7 +2465,7 @@ var async;
       _isolate_helper.enterJsAsync();
       self.setImmediate(_js_helper.convertDartClosureToJS(internalCallback, 0));
     }
-    static [_scheduleImmediateWithTimer](callback) {
+    static [_scheduleImmediateWithTimer$](callback) {
       Timer._createTimer(core.Duration.ZERO, callback);
     }
   }
@@ -2489,22 +2489,22 @@ var async;
   let _stream = Symbol('_stream');
   let StreamView$ = dart.generic(function(T) {
     class StreamView extends Stream$(T) {
-      StreamView($_stream) {
-        this[_stream] = $_stream;
+      StreamView(stream$) {
+        this[_stream] = stream$;
         super.Stream();
       }
       get isBroadcast() {
         return this[_stream].isBroadcast;
       }
-      asBroadcastStream(opt$) {
-        let onListen = opt$ && 'onListen' in opt$ ? opt$.onListen : null;
-        let onCancel = opt$ && 'onCancel' in opt$ ? opt$.onCancel : null;
+      asBroadcastStream(opts) {
+        let onListen = opts && 'onListen' in opts ? opts.onListen : null;
+        let onCancel = opts && 'onCancel' in opts ? opts.onCancel : null;
         return this[_stream].asBroadcastStream({onListen: onListen, onCancel: onCancel});
       }
-      listen(onData, opt$) {
-        let onError = opt$ && 'onError' in opt$ ? opt$.onError : null;
-        let onDone = opt$ && 'onDone' in opt$ ? opt$.onDone : null;
-        let cancelOnError = opt$ && 'cancelOnError' in opt$ ? opt$.cancelOnError : null;
+      listen(onData, opts) {
+        let onError = opts && 'onError' in opts ? opts.onError : null;
+        let onDone = opts && 'onDone' in opts ? opts.onDone : null;
+        let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : null;
         return this[_stream].listen(onData, {onError: onError, onDone: onDone, cancelOnError: cancelOnError});
       }
     }
@@ -2528,8 +2528,8 @@ var async;
       StreamTransformer(transformer) {
         return new _StreamSubscriptionTransformer(transformer);
       }
-      StreamTransformer$fromHandlers(opt$) {
-        return new _StreamHandlerTransformer(opt$);
+      StreamTransformer$fromHandlers(opts) {
+        return new _StreamHandlerTransformer(opts);
       }
     }
     dart.defineNamedConstructor(StreamTransformer, 'fromHandlers');
@@ -2547,8 +2547,8 @@ var async;
   let StreamIterator = StreamIterator$(dart.dynamic);
   let _ControllerEventSinkWrapper$ = dart.generic(function(T) {
     class _ControllerEventSinkWrapper extends core.Object {
-      _ControllerEventSinkWrapper($_sink) {
-        this[_sink] = $_sink;
+      _ControllerEventSinkWrapper(sink$) {
+        this[_sink] = sink$;
       }
       add(data) {
         this[_sink].add(data);
@@ -2567,21 +2567,21 @@ var async;
   let _ControllerEventSinkWrapper = _ControllerEventSinkWrapper$(dart.dynamic);
   let StreamController$ = dart.generic(function(T) {
     class StreamController extends core.Object {
-      StreamController(opt$) {
-        let onListen = opt$ && 'onListen' in opt$ ? opt$.onListen : null;
-        let onPause = opt$ && 'onPause' in opt$ ? opt$.onPause : null;
-        let onResume = opt$ && 'onResume' in opt$ ? opt$.onResume : null;
-        let onCancel = opt$ && 'onCancel' in opt$ ? opt$.onCancel : null;
-        let sync = opt$ && 'sync' in opt$ ? opt$.sync : false;
+      StreamController(opts) {
+        let onListen = opts && 'onListen' in opts ? opts.onListen : null;
+        let onPause = opts && 'onPause' in opts ? opts.onPause : null;
+        let onResume = opts && 'onResume' in opts ? opts.onResume : null;
+        let onCancel = opts && 'onCancel' in opts ? opts.onCancel : null;
+        let sync = opts && 'sync' in opts ? opts.sync : false;
         if (dart.notNull(onListen === null) && dart.notNull(onPause === null) && dart.notNull(onResume === null) && dart.notNull(onCancel === null)) {
           return dart.as(sync ? new _NoCallbackSyncStreamController() : new _NoCallbackAsyncStreamController(), StreamController$(T));
         }
         return sync ? new _SyncStreamController(onListen, onPause, onResume, onCancel) : new _AsyncStreamController(onListen, onPause, onResume, onCancel);
       }
-      StreamController$broadcast(opt$) {
-        let onListen = opt$ && 'onListen' in opt$ ? opt$.onListen : null;
-        let onCancel = opt$ && 'onCancel' in opt$ ? opt$.onCancel : null;
-        let sync = opt$ && 'sync' in opt$ ? opt$.sync : false;
+      StreamController$broadcast(opts) {
+        let onListen = opts && 'onListen' in opts ? opts.onListen : null;
+        let onCancel = opts && 'onCancel' in opts ? opts.onCancel : null;
+        let sync = opts && 'sync' in opts ? opts.sync : false;
         return sync ? new _SyncBroadcastStreamController(onListen, onCancel) : new _AsyncBroadcastStreamController(onListen, onCancel);
       }
     }
@@ -2677,8 +2677,8 @@ var async;
         dart.assert(this[_isAddingStream]);
         return new core.StateError("Cannot add event while adding a stream");
       }
-      addStream(source, opt$) {
-        let cancelOnError = opt$ && 'cancelOnError' in opt$ ? opt$.cancelOnError : true;
+      addStream(source, opts) {
+        let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : true;
         if (!dart.notNull(this[_mayAddEvent]))
           throw this[_badEventState]();
         if (this[_isCanceled])
@@ -2787,9 +2787,9 @@ var async;
               result = dart.as(this[_onCancel](), Future);
             } catch (e) {
               let s = dart.stackTrace(e);
-              result = ((_) => {
-                _._asyncCompleteError(e, s);
-                return _;
+              result = ((_$) => {
+                _$._asyncCompleteError(e, s);
+                return _$;
               }).bind(this)(new _Future());
             }
 
@@ -2866,11 +2866,11 @@ var async;
   let _AsyncStreamControllerDispatch = _AsyncStreamControllerDispatch$(dart.dynamic);
   let _AsyncStreamController$ = dart.generic(function(T) {
     class _AsyncStreamController extends dart.mixin(_StreamController$(T), _AsyncStreamControllerDispatch$(T)) {
-      _AsyncStreamController($_onListen, $_onPause, $_onResume, $_onCancel) {
-        this[_onListen] = $_onListen;
-        this[_onPause] = $_onPause;
-        this[_onResume] = $_onResume;
-        this[_onCancel] = $_onCancel;
+      _AsyncStreamController(onListen$, onPause$, onResume$, onCancel$) {
+        this[_onListen] = onListen$;
+        this[_onPause] = onPause$;
+        this[_onResume] = onResume$;
+        this[_onCancel] = onCancel$;
         super._StreamController();
       }
     }
@@ -2879,11 +2879,11 @@ var async;
   let _AsyncStreamController = _AsyncStreamController$(dart.dynamic);
   let _SyncStreamController$ = dart.generic(function(T) {
     class _SyncStreamController extends dart.mixin(_StreamController$(T), _SyncStreamControllerDispatch$(T)) {
-      _SyncStreamController($_onListen, $_onPause, $_onResume, $_onCancel) {
-        this[_onListen] = $_onListen;
-        this[_onPause] = $_onPause;
-        this[_onResume] = $_onResume;
-        this[_onCancel] = $_onCancel;
+      _SyncStreamController(onListen$, onPause$, onResume$, onCancel$) {
+        this[_onListen] = onListen$;
+        this[_onPause] = onPause$;
+        this[_onResume] = onResume$;
+        this[_onCancel] = onCancel$;
         super._StreamController();
       }
     }
@@ -2926,8 +2926,8 @@ var async;
   let _target = Symbol('_target');
   let _StreamSinkWrapper$ = dart.generic(function(T) {
     class _StreamSinkWrapper extends core.Object {
-      _StreamSinkWrapper($_target) {
-        this[_target] = $_target;
+      _StreamSinkWrapper(target$) {
+        this[_target] = target$;
       }
       add(data) {
         this[_target].add(data);
@@ -2940,8 +2940,8 @@ var async;
       close() {
         return this[_target].close();
       }
-      addStream(source, opt$) {
-        let cancelOnError = opt$ && 'cancelOnError' in opt$ ? opt$.cancelOnError : true;
+      addStream(source, opts) {
+        let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : true;
         return this[_target].addStream(source, {cancelOnError: cancelOnError});
       }
       get done() {
@@ -3014,8 +3014,8 @@ var async;
   let _isUsed = Symbol('_isUsed');
   let _GeneratedStreamImpl$ = dart.generic(function(T) {
     class _GeneratedStreamImpl extends _StreamImpl$(T) {
-      _GeneratedStreamImpl($_pending) {
-        this[_pending] = $_pending;
+      _GeneratedStreamImpl(pending$) {
+        this[_pending] = pending$;
         this[_isUsed] = false;
         super._StreamImpl();
       }
@@ -3023,9 +3023,9 @@ var async;
         if (this[_isUsed])
           throw new core.StateError("Stream has already been listened to.");
         this[_isUsed] = true;
-        return ((_) => {
-          _._setPendingEvents(this[_pending]());
-          return _;
+        return ((_$) => {
+          _$._setPendingEvents(this[_pending]());
+          return _$;
         }).bind(this)(new _BufferingStreamSubscription(onData, onError, onDone, cancelOnError));
       }
     }
@@ -3218,8 +3218,8 @@ var async;
   let _isScheduled = Symbol('_isScheduled');
   let _DoneStreamSubscription$ = dart.generic(function(T) {
     class _DoneStreamSubscription extends core.Object {
-      _DoneStreamSubscription($_onDone) {
-        this[_onDone] = $_onDone;
+      _DoneStreamSubscription(onDone$) {
+        this[_onDone] = onDone$;
         this[_zone] = Zone.current;
         this[_state] = 0;
         this[_schedule]();
@@ -3295,8 +3295,8 @@ var async;
   let _isSubscriptionPaused = Symbol('_isSubscriptionPaused');
   let _AsBroadcastStream$ = dart.generic(function(T) {
     class _AsBroadcastStream extends Stream$(T) {
-      _AsBroadcastStream($_source, onListenHandler, onCancelHandler) {
-        this[_source] = $_source;
+      _AsBroadcastStream(source$, onListenHandler, onCancelHandler) {
+        this[_source] = source$;
         this[_onListenHandler] = dart.closureWrap(Zone.current.registerUnaryCallback(onListenHandler), "(StreamSubscription<dynamic>) → void");
         this[_onCancelHandler] = dart.closureWrap(Zone.current.registerUnaryCallback(onCancelHandler), "(StreamSubscription<dynamic>) → void");
         this[_zone] = Zone.current;
@@ -3308,10 +3308,10 @@ var async;
       get isBroadcast() {
         return true;
       }
-      listen(onData, opt$) {
-        let onError = opt$ && 'onError' in opt$ ? opt$.onError : null;
-        let onDone = opt$ && 'onDone' in opt$ ? opt$.onDone : null;
-        let cancelOnError = opt$ && 'cancelOnError' in opt$ ? opt$.cancelOnError : null;
+      listen(onData, opts) {
+        let onError = opts && 'onError' in opts ? opts.onError : null;
+        let onDone = opts && 'onDone' in opts ? opts.onDone : null;
+        let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : null;
         if (dart.notNull(this[_controller] === null) || dart.notNull(this[_controller].isClosed)) {
           return new _DoneStreamSubscription(onDone);
         }
@@ -3367,8 +3367,8 @@ var async;
   let _AsBroadcastStream = _AsBroadcastStream$(dart.dynamic);
   let _BroadcastSubscriptionWrapper$ = dart.generic(function(T) {
     class _BroadcastSubscriptionWrapper extends core.Object {
-      _BroadcastSubscriptionWrapper($_stream) {
-        this[_stream] = $_stream;
+      _BroadcastSubscriptionWrapper(stream$) {
+        this[_stream] = stream$;
       }
       onData(handleData) {
         throw new core.UnsupportedError("Cannot change handlers of asBroadcastStream source subscription.");
@@ -3403,20 +3403,20 @@ var async;
     return _BroadcastSubscriptionWrapper;
   });
   let _BroadcastSubscriptionWrapper = _BroadcastSubscriptionWrapper$(dart.dynamic);
-  let _current = Symbol('_current');
+  let _current$ = Symbol('_current');
   let _futureOrPrefetch = Symbol('_futureOrPrefetch');
   let _clear = Symbol('_clear');
   let _StreamIteratorImpl$ = dart.generic(function(T) {
     class _StreamIteratorImpl extends core.Object {
       _StreamIteratorImpl(stream) {
         this[_subscription] = null;
-        this[_current] = null;
+        this[_current$] = null;
         this[_futureOrPrefetch] = null;
         this[_state] = _StreamIteratorImpl._STATE_FOUND;
         this[_subscription] = stream.listen(this[_onData], {onError: this[_onError], onDone: this[_onDone], cancelOnError: true});
       }
       get current() {
-        return this[_current];
+        return this[_current$];
       }
       moveNext() {
         if (this[_state] === _StreamIteratorImpl._STATE_DONE) {
@@ -3427,7 +3427,7 @@ var async;
         }
         if (this[_state] === _StreamIteratorImpl._STATE_FOUND) {
           this[_state] = _StreamIteratorImpl._STATE_MOVING;
-          this[_current] = null;
+          this[_current$] = null;
           this[_futureOrPrefetch] = new _Future();
           return dart.as(this[_futureOrPrefetch], Future$(core.bool));
         } else {
@@ -3435,7 +3435,7 @@ var async;
           switch (this[_state]) {
             case _StreamIteratorImpl._STATE_EXTRA_DATA:
               this[_state] = _StreamIteratorImpl._STATE_FOUND;
-              this[_current] = dart.as(this[_futureOrPrefetch], T);
+              this[_current$] = dart.as(this[_futureOrPrefetch], T);
               this[_futureOrPrefetch] = null;
               this[_subscription].resume();
               return new _Future.immediate(true);
@@ -3452,7 +3452,7 @@ var async;
       [_clear]() {
         this[_subscription] = null;
         this[_futureOrPrefetch] = null;
-        this[_current] = null;
+        this[_current$] = null;
         this[_state] = _StreamIteratorImpl._STATE_DONE;
       }
       cancel() {
@@ -3468,7 +3468,7 @@ var async;
       }
       [_onData](data) {
         if (this[_state] === _StreamIteratorImpl._STATE_MOVING) {
-          this[_current] = data;
+          this[_current$] = data;
           let hasNext = dart.as(this[_futureOrPrefetch], _Future$(core.bool));
           this[_futureOrPrefetch] = null;
           this[_state] = _StreamIteratorImpl._STATE_FOUND;
@@ -3568,17 +3568,17 @@ var async;
   let _handleDone = Symbol('_handleDone');
   let _ForwardingStream$ = dart.generic(function(S, T) {
     class _ForwardingStream extends Stream$(T) {
-      _ForwardingStream($_source) {
-        this[_source] = $_source;
+      _ForwardingStream(source$) {
+        this[_source] = source$;
         super.Stream();
       }
       get isBroadcast() {
         return this[_source].isBroadcast;
       }
-      listen(onData, opt$) {
-        let onError = opt$ && 'onError' in opt$ ? opt$.onError : null;
-        let onDone = opt$ && 'onDone' in opt$ ? opt$.onDone : null;
-        let cancelOnError = opt$ && 'cancelOnError' in opt$ ? opt$.cancelOnError : null;
+      listen(onData, opts) {
+        let onError = opts && 'onError' in opts ? opts.onError : null;
+        let onDone = opts && 'onDone' in opts ? opts.onDone : null;
+        let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : null;
         cancelOnError = core.identical(true, cancelOnError);
         return this[_createSubscription](onData, onError, onDone, cancelOnError);
       }
@@ -3601,8 +3601,8 @@ var async;
   let _ForwardingStream = _ForwardingStream$(dart.dynamic, dart.dynamic);
   let _ForwardingStreamSubscription$ = dart.generic(function(S, T) {
     class _ForwardingStreamSubscription extends _BufferingStreamSubscription$(T) {
-      _ForwardingStreamSubscription($_stream, onData, onError, onDone, cancelOnError) {
-        this[_stream] = $_stream;
+      _ForwardingStreamSubscription(stream$, onData, onError, onDone, cancelOnError) {
+        this[_stream] = stream$;
         this[_subscription] = null;
         super._BufferingStreamSubscription(onData, onError, onDone, cancelOnError);
         this[_subscription] = this[_stream][_source].listen(this[_handleData], {onError: this[_handleError], onDone: this[_handleDone]});
@@ -3911,8 +3911,8 @@ var async;
   let _DistinctStream = _DistinctStream$(dart.dynamic);
   let _EventSinkWrapper$ = dart.generic(function(T) {
     class _EventSinkWrapper extends core.Object {
-      _EventSinkWrapper($_sink) {
-        this[_sink] = $_sink;
+      _EventSinkWrapper(sink$) {
+        this[_sink] = sink$;
       }
       add(data) {
         this[_sink]._add(data);
@@ -4019,8 +4019,8 @@ var async;
   let _sinkMapper = Symbol('_sinkMapper');
   let _StreamSinkTransformer$ = dart.generic(function(S, T) {
     class _StreamSinkTransformer extends core.Object {
-      _StreamSinkTransformer($_sinkMapper) {
-        this[_sinkMapper] = $_sinkMapper;
+      _StreamSinkTransformer(sinkMapper) {
+        this[_sinkMapper] = sinkMapper;
       }
       bind(stream) {
         return new _BoundSinkStream(stream, this[_sinkMapper]);
@@ -4034,15 +4034,15 @@ var async;
       get isBroadcast() {
         return this[_stream].isBroadcast;
       }
-      _BoundSinkStream($_stream, $_sinkMapper) {
-        this[_stream] = $_stream;
-        this[_sinkMapper] = $_sinkMapper;
+      _BoundSinkStream(stream$, sinkMapper) {
+        this[_stream] = stream$;
+        this[_sinkMapper] = sinkMapper;
         super.Stream();
       }
-      listen(onData, opt$) {
-        let onError = opt$ && 'onError' in opt$ ? opt$.onError : null;
-        let onDone = opt$ && 'onDone' in opt$ ? opt$.onDone : null;
-        let cancelOnError = opt$ && 'cancelOnError' in opt$ ? opt$.cancelOnError : null;
+      listen(onData, opts) {
+        let onError = opts && 'onError' in opts ? opts.onError : null;
+        let onDone = opts && 'onDone' in opts ? opts.onDone : null;
+        let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : null;
         cancelOnError = core.identical(true, cancelOnError);
         let subscription = dart.as(new _SinkTransformerStreamSubscription(this[_stream], dart.closureWrap(this[_sinkMapper], "(EventSink<dynamic>) → EventSink"), onData, onError, onDone, cancelOnError), StreamSubscription$(T));
         return subscription;
@@ -4053,11 +4053,11 @@ var async;
   let _BoundSinkStream = _BoundSinkStream$(dart.dynamic, dart.dynamic);
   let _HandlerEventSink$ = dart.generic(function(S, T) {
     class _HandlerEventSink extends core.Object {
-      _HandlerEventSink($_handleData, $_handleError, $_handleDone, $_sink) {
-        this[_handleData] = $_handleData;
-        this[_handleError] = $_handleError;
-        this[_handleDone] = $_handleDone;
-        this[_sink] = $_sink;
+      _HandlerEventSink(handleData$, handleError$, handleDone$, sink$) {
+        this[_handleData] = handleData$;
+        this[_handleError] = handleError$;
+        this[_handleDone] = handleDone$;
+        this[_sink] = sink$;
       }
       add(data) {
         return this[_handleData](data, this[_sink]);
@@ -4074,15 +4074,15 @@ var async;
     return _HandlerEventSink;
   });
   let _HandlerEventSink = _HandlerEventSink$(dart.dynamic, dart.dynamic);
-  let _defaultHandleData = Symbol('_defaultHandleData');
-  let _defaultHandleError = Symbol('_defaultHandleError');
-  let _defaultHandleDone = Symbol('_defaultHandleDone');
+  let _defaultHandleData$ = Symbol('_defaultHandleData');
+  let _defaultHandleError$ = Symbol('_defaultHandleError');
+  let _defaultHandleDone$ = Symbol('_defaultHandleDone');
   let _StreamHandlerTransformer$ = dart.generic(function(S, T) {
     class _StreamHandlerTransformer extends _StreamSinkTransformer$(S, T) {
-      _StreamHandlerTransformer(opt$) {
-        let handleData = opt$ && 'handleData' in opt$ ? opt$.handleData : null;
-        let handleError = opt$ && 'handleError' in opt$ ? opt$.handleError : null;
-        let handleDone = opt$ && 'handleDone' in opt$ ? opt$.handleDone : null;
+      _StreamHandlerTransformer(opts) {
+        let handleData = opts && 'handleData' in opts ? opts.handleData : null;
+        let handleError = opts && 'handleError' in opts ? opts.handleError : null;
+        let handleDone = opts && 'handleDone' in opts ? opts.handleDone : null;
         super._StreamSinkTransformer(dart.closureWrap((outputSink) => {
           if (handleData === null)
             handleData = dart.closureWrap(_defaultHandleData, "(S, EventSink<T>) → void");
@@ -4096,13 +4096,13 @@ var async;
       bind(stream) {
         return super.bind(stream);
       }
-      static [_defaultHandleData](data, sink) {
+      static [_defaultHandleData$](data, sink) {
         sink.add(data);
       }
-      static [_defaultHandleError](error, stackTrace, sink) {
+      static [_defaultHandleError$](error, stackTrace, sink) {
         sink.addError(error);
       }
-      static [_defaultHandleDone](sink) {
+      static [_defaultHandleDone$](sink) {
         sink.close();
       }
     }
@@ -4112,8 +4112,8 @@ var async;
   let _transformer = Symbol('_transformer');
   let _StreamSubscriptionTransformer$ = dart.generic(function(S, T) {
     class _StreamSubscriptionTransformer extends core.Object {
-      _StreamSubscriptionTransformer($_transformer) {
-        this[_transformer] = $_transformer;
+      _StreamSubscriptionTransformer(transformer$) {
+        this[_transformer] = transformer$;
       }
       bind(stream) {
         return new _BoundSubscriptionStream(stream, this[_transformer]);
@@ -4124,15 +4124,15 @@ var async;
   let _StreamSubscriptionTransformer = _StreamSubscriptionTransformer$(dart.dynamic, dart.dynamic);
   let _BoundSubscriptionStream$ = dart.generic(function(S, T) {
     class _BoundSubscriptionStream extends Stream$(T) {
-      _BoundSubscriptionStream($_stream, $_transformer) {
-        this[_stream] = $_stream;
-        this[_transformer] = $_transformer;
+      _BoundSubscriptionStream(stream$, transformer$) {
+        this[_stream] = stream$;
+        this[_transformer] = transformer$;
         super.Stream();
       }
-      listen(onData, opt$) {
-        let onError = opt$ && 'onError' in opt$ ? opt$.onError : null;
-        let onDone = opt$ && 'onDone' in opt$ ? opt$.onDone : null;
-        let cancelOnError = opt$ && 'cancelOnError' in opt$ ? opt$.cancelOnError : null;
+      listen(onData, opts) {
+        let onError = opts && 'onError' in opts ? opts.onError : null;
+        let onDone = opts && 'onDone' in opts ? opts.onDone : null;
+        let cancelOnError = opts && 'cancelOnError' in opts ? opts.cancelOnError : null;
         cancelOnError = core.identical(true, cancelOnError);
         let result = this[_transformer](this[_stream], cancelOnError);
         result.onData(onData);
@@ -4177,48 +4177,48 @@ var async;
   }
   dart.defineNamedConstructor(Timer, 'periodic');
   class _ZoneFunction extends core.Object {
-    _ZoneFunction(zone, function) {
+    _ZoneFunction(zone, func) {
       this.zone = zone;
-      this['function'] = function;
+      this.function = func;
     }
   }
   class ZoneSpecification extends core.Object {
-    ZoneSpecification(opt$) {
-      return new _ZoneSpecification(opt$);
-    }
-    ZoneSpecification$from(other, opt$) {
-      let handleUncaughtError = opt$ && 'handleUncaughtError' in opt$ ? opt$.handleUncaughtError : null;
-      let run = opt$ && 'run' in opt$ ? opt$.run : null;
-      let runUnary = opt$ && 'runUnary' in opt$ ? opt$.runUnary : null;
-      let runBinary = opt$ && 'runBinary' in opt$ ? opt$.runBinary : null;
-      let registerCallback = opt$ && 'registerCallback' in opt$ ? opt$.registerCallback : null;
-      let registerUnaryCallback = opt$ && 'registerUnaryCallback' in opt$ ? opt$.registerUnaryCallback : null;
-      let registerBinaryCallback = opt$ && 'registerBinaryCallback' in opt$ ? opt$.registerBinaryCallback : null;
-      let errorCallback = opt$ && 'errorCallback' in opt$ ? opt$.errorCallback : null;
-      let scheduleMicrotask = opt$ && 'scheduleMicrotask' in opt$ ? opt$.scheduleMicrotask : null;
-      let createTimer = opt$ && 'createTimer' in opt$ ? opt$.createTimer : null;
-      let createPeriodicTimer = opt$ && 'createPeriodicTimer' in opt$ ? opt$.createPeriodicTimer : null;
-      let print = opt$ && 'print' in opt$ ? opt$.print : null;
-      let fork = opt$ && 'fork' in opt$ ? opt$.fork : null;
+    ZoneSpecification(opts) {
+      return new _ZoneSpecification(opts);
+    }
+    ZoneSpecification$from(other, opts) {
+      let handleUncaughtError = opts && 'handleUncaughtError' in opts ? opts.handleUncaughtError : null;
+      let run = opts && 'run' in opts ? opts.run : null;
+      let runUnary = opts && 'runUnary' in opts ? opts.runUnary : null;
+      let runBinary = opts && 'runBinary' in opts ? opts.runBinary : null;
+      let registerCallback = opts && 'registerCallback' in opts ? opts.registerCallback : null;
+      let registerUnaryCallback = opts && 'registerUnaryCallback' in opts ? opts.registerUnaryCallback : null;
+      let registerBinaryCallback = opts && 'registerBinaryCallback' in opts ? opts.registerBinaryCallback : null;
+      let errorCallback = opts && 'errorCallback' in opts ? opts.errorCallback : null;
+      let scheduleMicrotask = opts && 'scheduleMicrotask' in opts ? opts.scheduleMicrotask : null;
+      let createTimer = opts && 'createTimer' in opts ? opts.createTimer : null;
+      let createPeriodicTimer = opts && 'createPeriodicTimer' in opts ? opts.createPeriodicTimer : null;
+      let print = opts && 'print' in opts ? opts.print : null;
+      let fork = opts && 'fork' in opts ? opts.fork : null;
       return new ZoneSpecification({handleUncaughtError: dart.as(handleUncaughtError !== null ? handleUncaughtError : other.handleUncaughtError, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, dynamic, StackTrace) → dynamic")), run: dart.as(run !== null ? run : other.run, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, () → dynamic) → dynamic")), runUnary: dart.as(runUnary !== null ? runUnary : other.runUnary, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, (dynamic) → dynamic, dynamic) → dynamic")), runBinary: dart.as(runBinary !== null ? runBinary : other.runBinary, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, (dynamic, dynamic) → dynamic, dynamic, dynamic) → dynamic")), registerCallback: dart.as(registerCallback !== null ? registerCallback : other.registerCallback, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, () → dynamic) → ZoneCallback")), registerUnaryCallback: dart.as(registerUnaryCallback !== null ? registerUnaryCallback : other.registerUnaryCallback, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, (dynamic) → dynamic) → ZoneUnaryCallback")), registerBinaryCallback: dart.as(registerBinaryCallback !== null ? registerBinaryCallback : other.registerBinaryCallback, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, (dynamic, dynamic) → dynamic) → ZoneBinaryCallback")), errorCallback: dart.as(errorCallback !== null ? errorCallback : other.errorCallback, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, Object, StackTrace) → AsyncError")), scheduleMicrotask: dart.as(scheduleMicrotask !== null ? scheduleMicrotask : other.scheduleMicrotask, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, () → dynamic) → void")), createTimer: dart.as(createTimer !== null ? createTimer : other.createTimer, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, Duration, () → void) → Timer")), createPeriodicTimer: dart.as(createPeriodicTimer !== null ? createPeriodicTimer : other.createPeriodicTimer, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, Duration, (Timer) → void) → Timer")), print: dart.as(print !== null ? print : other.print, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, String) → void")), fork: dart.as(fork !== null ? fork : other.fork, dart.throw_("Unimplemented type (Zone, ZoneDelegate, Zone, ZoneSpecification, Map<dynamic, dynamic>) → Zone"))});
     }
   }
   dart.defineNamedConstructor(ZoneSpecification, 'from');
   class _ZoneSpecification extends core.Object {
-    _ZoneSpecification(opt$) {
-      let handleUncaughtError = opt$ && 'handleUncaughtError' in opt$ ? opt$.handleUncaughtError : null;
-      let run = opt$ && 'run' in opt$ ? opt$.run : null;
-      let runUnary = opt$ && 'runUnary' in opt$ ? opt$.runUnary : null;
-      let runBinary = opt$ && 'runBinary' in opt$ ? opt$.runBinary : null;
-      let registerCallback = opt$ && 'registerCallback' in opt$ ? opt$.registerCallback : null;
-      let registerUnaryCallback = opt$ && 'registerUnaryCallback' in opt$ ? opt$.registerUnaryCallback : null;
-      let registerBinaryCallback = opt$ && 'registerBinaryCallback' in opt$ ? opt$.registerBinaryCallback : null;
-      let errorCallback = opt$ && 'errorCallback' in opt$ ? opt$.errorCallback : null;
-      let scheduleMicrotask = opt$ && 'scheduleMicrotask' in opt$ ? opt$.scheduleMicrotask : null;
-      let createTimer = opt$ && 'createTimer' in opt$ ? opt$.createTimer : null;
-      let createPeriodicTimer = opt$ && 'createPeriodicTimer' in opt$ ? opt$.createPeriodicTimer : null;
-      let print = opt$ && 'print' in opt$ ? opt$.print : null;
-      let fork = opt$ && 'fork' in opt$ ? opt$.fork : null;
+    _ZoneSpecification(opts) {
+      let handleUncaughtError = opts && 'handleUncaughtError' in opts ? opts.handleUncaughtError : null;
+      let run = opts && 'run' in opts ? opts.run : null;
+      let runUnary = opts && 'runUnary' in opts ? opts.runUnary : null;
+      let runBinary = opts && 'runBinary' in opts ? opts.runBinary : null;
+      let registerCallback = opts && 'registerCallback' in opts ? opts.registerCallback : null;
+      let registerUnaryCallback = opts && 'registerUnaryCallback' in opts ? opts.registerUnaryCallback : null;
+      let registerBinaryCallback = opts && 'registerBinaryCallback' in opts ? opts.registerBinaryCallback : null;
+      let errorCallback = opts && 'errorCallback' in opts ? opts.errorCallback : null;
+      let scheduleMicrotask = opts && 'scheduleMicrotask' in opts ? opts.scheduleMicrotask : null;
+      let createTimer = opts && 'createTimer' in opts ? opts.createTimer : null;
+      let createPeriodicTimer = opts && 'createPeriodicTimer' in opts ? opts.createPeriodicTimer : null;
+      let print = opts && 'print' in opts ? opts.print : null;
+      let fork = opts && 'fork' in opts ? opts.fork : null;
       this.handleUncaughtError = handleUncaughtError;
       this.run = run;
       this.runUnary = runUnary;
@@ -4253,7 +4253,7 @@ var async;
     }
     static [_leave](previous) {
       dart.assert(previous !== null);
-      Zone[_current] = previous;
+      Zone[_current$] = previous;
     }
   }
   dart.defineNamedConstructor(Zone, '_');
@@ -4279,75 +4279,75 @@ var async;
   let _print = Symbol('_print');
   let _fork = Symbol('_fork');
   class _ZoneDelegate extends core.Object {
-    _ZoneDelegate($_delegationTarget) {
-      this[_delegationTarget] = $_delegationTarget;
+    _ZoneDelegate(delegationTarget) {
+      this[_delegationTarget] = delegationTarget;
     }
     handleUncaughtError(zone, error, stackTrace) {
       let implementation = this[_delegationTarget][_handleUncaughtError];
       let implZone = implementation.zone;
-      return dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, error, stackTrace);
+      return dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, error, stackTrace);
     }
     run(zone, f) {
       let implementation = this[_delegationTarget][_run];
       let implZone = implementation.zone;
-      return dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, f);
+      return dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, f);
     }
     runUnary(zone, f, arg) {
       let implementation = this[_delegationTarget][_runUnary];
       let implZone = implementation.zone;
-      return dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, f, arg);
+      return dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, f, arg);
     }
     runBinary(zone, f, arg1, arg2) {
       let implementation = this[_delegationTarget][_runBinary];
       let implZone = implementation.zone;
-      return dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, f, arg1, arg2);
+      return dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, f, arg1, arg2);
     }
     registerCallback(zone, f) {
       let implementation = this[_delegationTarget][_registerCallback];
       let implZone = implementation.zone;
-      return dart.as(dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, f), ZoneCallback);
+      return dart.as(dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, f), ZoneCallback);
     }
     registerUnaryCallback(zone, f) {
       let implementation = this[_delegationTarget][_registerUnaryCallback];
       let implZone = implementation.zone;
-      return dart.as(dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, f), ZoneUnaryCallback);
+      return dart.as(dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, f), ZoneUnaryCallback);
     }
     registerBinaryCallback(zone, f) {
       let implementation = this[_delegationTarget][_registerBinaryCallback];
       let implZone = implementation.zone;
-      return dart.as(dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, f), ZoneBinaryCallback);
+      return dart.as(dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, f), ZoneBinaryCallback);
     }
     errorCallback(zone, error, stackTrace) {
       let implementation = this[_delegationTarget][_errorCallback];
       let implZone = implementation.zone;
       if (core.identical(implZone, _ROOT_ZONE))
         return null;
-      return dart.as(dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, error, stackTrace), AsyncError);
+      return dart.as(dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, error, stackTrace), AsyncError);
     }
     scheduleMicrotask(zone, f) {
       let implementation = this[_delegationTarget][_scheduleMicrotask];
       let implZone = implementation.zone;
-      dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, f);
+      dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, f);
     }
     createTimer(zone, duration, f) {
       let implementation = this[_delegationTarget][_createTimer];
       let implZone = implementation.zone;
-      return dart.as(dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, duration, f), Timer);
+      return dart.as(dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, duration, f), Timer);
     }
     createPeriodicTimer(zone, period, f) {
       let implementation = this[_delegationTarget][_createPeriodicTimer];
       let implZone = implementation.zone;
-      return dart.as(dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, period, f), Timer);
+      return dart.as(dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, period, f), Timer);
     }
     print(zone, line) {
       let implementation = this[_delegationTarget][_print];
       let implZone = implementation.zone;
-      dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, line);
+      dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, line);
     }
     fork(zone, specification, zoneValues) {
       let implementation = this[_delegationTarget][_fork];
       let implZone = implementation.zone;
-      return dart.as(dart.dinvokef(implementation['function'], implZone, _parentDelegate(implZone), zone, specification, zoneValues), Zone);
+      return dart.as(dart.dinvokef(implementation.function, implZone, _parentDelegate(implZone), zone, specification, zoneValues), Zone);
     }
   }
   class _Zone extends core.Object {
@@ -4366,9 +4366,9 @@ var async;
       this[_delegateCache] = new _ZoneDelegate(this);
       return this[_delegateCache];
     }
-    _CustomZone(parent, specification, $_map) {
+    _CustomZone(parent, specification, map) {
       this.parent = parent;
-      this[_map] = $_map;
+      this[_map] = map;
       this[_runUnary] = null;
       this[_run] = null;
       this[_runBinary] = null;
@@ -4428,8 +4428,8 @@ var async;
       }
 
     }
-    bindCallback(f, opt$) {
-      let runGuarded = opt$ && 'runGuarded' in opt$ ? opt$.runGuarded : true;
+    bindCallback(f, opts) {
+      let runGuarded = opts && 'runGuarded' in opts ? opts.runGuarded : true;
       let registered = this.registerCallback(f);
       if (runGuarded) {
         return (() => this.runGuarded(registered)).bind(this);
@@ -4437,8 +4437,8 @@ var async;
         return (() => this.run(registered)).bind(this);
       }
     }
-    bindUnaryCallback(f, opt$) {
-      let runGuarded = opt$ && 'runGuarded' in opt$ ? opt$.runGuarded : true;
+    bindUnaryCallback(f, opts) {
+      let runGuarded = opts && 'runGuarded' in opts ? opts.runGuarded : true;
       let registered = this.registerUnaryCallback(f);
       if (runGuarded) {
         return ((arg) => this.runUnaryGuarded(registered, arg)).bind(this);
@@ -4446,8 +4446,8 @@ var async;
         return ((arg) => this.runUnary(registered, arg)).bind(this);
       }
     }
-    bindBinaryCallback(f, opt$) {
-      let runGuarded = opt$ && 'runGuarded' in opt$ ? opt$.runGuarded : true;
+    bindBinaryCallback(f, opts) {
+      let runGuarded = opts && 'runGuarded' in opts ? opts.runGuarded : true;
       let registered = this.registerBinaryCallback(f);
       if (runGuarded) {
         return ((arg1, arg2) => this.runBinaryGuarded(registered, arg1, arg2)).bind(this);
@@ -4473,51 +4473,51 @@ var async;
       let implementation = this[_handleUncaughtError];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, error, stackTrace);
+      return dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, error, stackTrace);
     }
-    fork(opt$) {
-      let specification = opt$ && 'specification' in opt$ ? opt$.specification : null;
-      let zoneValues = opt$ && 'zoneValues' in opt$ ? opt$.zoneValues : null;
+    fork(opts) {
+      let specification = opts && 'specification' in opts ? opts.specification : null;
+      let zoneValues = opts && 'zoneValues' in opts ? opts.zoneValues : null;
       let implementation = this[_fork];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.as(dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, specification, zoneValues), Zone);
+      return dart.as(dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, specification, zoneValues), Zone);
     }
     run(f) {
       let implementation = this[_run];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, f);
+      return dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, f);
     }
     runUnary(f, arg) {
       let implementation = this[_runUnary];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, f, arg);
+      return dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, f, arg);
     }
     runBinary(f, arg1, arg2) {
       let implementation = this[_runBinary];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, f, arg1, arg2);
+      return dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, f, arg1, arg2);
     }
     registerCallback(f) {
       let implementation = this[_registerCallback];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.as(dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, f), ZoneCallback);
+      return dart.as(dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, f), ZoneCallback);
     }
     registerUnaryCallback(f) {
       let implementation = this[_registerUnaryCallback];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.as(dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, f), ZoneUnaryCallback);
+      return dart.as(dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, f), ZoneUnaryCallback);
     }
     registerBinaryCallback(f) {
       let implementation = this[_registerBinaryCallback];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.as(dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, f), ZoneBinaryCallback);
+      return dart.as(dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, f), ZoneBinaryCallback);
     }
     errorCallback(error, stackTrace) {
       let implementation = this[_errorCallback];
@@ -4526,31 +4526,31 @@ var async;
       if (core.identical(implementationZone, _ROOT_ZONE))
         return null;
       let parentDelegate = _parentDelegate(dart.as(implementationZone, _Zone));
-      return dart.as(dart.dinvokef(implementation['function'], implementationZone, parentDelegate, this, error, stackTrace), AsyncError);
+      return dart.as(dart.dinvokef(implementation.function, implementationZone, parentDelegate, this, error, stackTrace), AsyncError);
     }
     scheduleMicrotask(f) {
       let implementation = this[_scheduleMicrotask];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, f);
+      return dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, f);
     }
     createTimer(duration, f) {
       let implementation = this[_createTimer];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.as(dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, duration, f), Timer);
+      return dart.as(dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, duration, f), Timer);
     }
     createPeriodicTimer(duration, f) {
       let implementation = this[_createPeriodicTimer];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.as(dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, duration, f), Timer);
+      return dart.as(dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, duration, f), Timer);
     }
     print(line) {
       let implementation = this[_print];
       dart.assert(implementation !== null);
       let parentDelegate = _parentDelegate(implementation.zone);
-      return dart.dinvokef(implementation['function'], implementation.zone, parentDelegate, this, line);
+      return dart.dinvokef(implementation.function, implementation.zone, parentDelegate, this, line);
     }
   }
   // Function _rootHandleUncaughtError: (Zone, ZoneDelegate, Zone, dynamic, StackTrace) → void
@@ -4561,7 +4561,7 @@ var async;
   }
   // Function _rootRun: (Zone, ZoneDelegate, Zone, () → dynamic) → dynamic
   function _rootRun(self, parent, zone, f) {
-    if (dart.equals(Zone[_current], zone))
+    if (dart.equals(Zone[_current$], zone))
       return f();
     let old = Zone._enter(zone);
     try {
@@ -4572,7 +4572,7 @@ var async;
   }
   // Function _rootRunUnary: (Zone, ZoneDelegate, Zone, (dynamic) → dynamic, dynamic) → dynamic
   function _rootRunUnary(self, parent, zone, f, arg) {
-    if (dart.equals(Zone[_current], zone))
+    if (dart.equals(Zone[_current$], zone))
       return dart.dinvokef(f, arg);
     let old = Zone._enter(zone);
     try {
@@ -4583,7 +4583,7 @@ var async;
   }
   // Function _rootRunBinary: (Zone, ZoneDelegate, Zone, (dynamic, dynamic) → dynamic, dynamic, dynamic) → dynamic
   function _rootRunBinary(self, parent, zone, f, arg1, arg2) {
-    if (dart.equals(Zone[_current], zone))
+    if (dart.equals(Zone[_current$], zone))
       return dart.dinvokef(f, arg1, arg2);
     let old = Zone._enter(zone);
     try {
@@ -4758,7 +4758,7 @@ var async;
     }
     runGuarded(f) {
       try {
-        if (core.identical(_ROOT_ZONE, Zone[_current])) {
+        if (core.identical(_ROOT_ZONE, Zone[_current$])) {
           return f();
         }
         return _rootRun(null, null, this, f);
@@ -4770,7 +4770,7 @@ var async;
     }
     runUnaryGuarded(f, arg) {
       try {
-        if (core.identical(_ROOT_ZONE, Zone[_current])) {
+        if (core.identical(_ROOT_ZONE, Zone[_current$])) {
           return dart.dinvokef(f, arg);
         }
         return _rootRunUnary(null, null, this, f, arg);
@@ -4782,7 +4782,7 @@ var async;
     }
     runBinaryGuarded(f, arg1, arg2) {
       try {
-        if (core.identical(_ROOT_ZONE, Zone[_current])) {
+        if (core.identical(_ROOT_ZONE, Zone[_current$])) {
           return dart.dinvokef(f, arg1, arg2);
         }
         return _rootRunBinary(null, null, this, f, arg1, arg2);
@@ -4792,24 +4792,24 @@ var async;
       }
 
     }
-    bindCallback(f, opt$) {
-      let runGuarded = opt$ && 'runGuarded' in opt$ ? opt$.runGuarded : true;
+    bindCallback(f, opts) {
+      let runGuarded = opts && 'runGuarded' in opts ? opts.runGuarded : true;
       if (runGuarded) {
         return (() => this.runGuarded(f)).bind(this);
       } else {
         return (() => this.run(f)).bind(this);
       }
     }
-    bindUnaryCallback(f, opt$) {
-      let runGuarded = opt$ && 'runGuarded' in opt$ ? opt$.runGuarded : true;
+    bindUnaryCallback(f, opts) {
+      let runGuarded = opts && 'runGuarded' in opts ? opts.runGuarded : true;
       if (runGuarded) {
         return ((arg) => this.runUnaryGuarded(f, arg)).bind(this);
       } else {
         return ((arg) => this.runUnary(f, arg)).bind(this);
       }
     }
-    bindBinaryCallback(f, opt$) {
-      let runGuarded = opt$ && 'runGuarded' in opt$ ? opt$.runGuarded : true;
+    bindBinaryCallback(f, opts) {
+      let runGuarded = opts && 'runGuarded' in opts ? opts.runGuarded : true;
       if (runGuarded) {
         return ((arg1, arg2) => this.runBinaryGuarded(f, arg1, arg2)).bind(this);
       } else {
@@ -4822,23 +4822,23 @@ var async;
     handleUncaughtError(error, stackTrace) {
       return _rootHandleUncaughtError(null, null, this, error, stackTrace);
     }
-    fork(opt$) {
-      let specification = opt$ && 'specification' in opt$ ? opt$.specification : null;
-      let zoneValues = opt$ && 'zoneValues' in opt$ ? opt$.zoneValues : null;
+    fork(opts) {
+      let specification = opts && 'specification' in opts ? opts.specification : null;
+      let zoneValues = opts && 'zoneValues' in opts ? opts.zoneValues : null;
       return _rootFork(null, null, this, specification, zoneValues);
     }
     run(f) {
-      if (core.identical(Zone[_current], _ROOT_ZONE))
+      if (core.identical(Zone[_current$], _ROOT_ZONE))
         return f();
       return _rootRun(null, null, this, f);
     }
     runUnary(f, arg) {
-      if (core.identical(Zone[_current], _ROOT_ZONE))
+      if (core.identical(Zone[_current$], _ROOT_ZONE))
         return dart.dinvokef(f, arg);
       return _rootRunUnary(null, null, this, f, arg);
     }
     runBinary(f, arg1, arg2) {
-      if (core.identical(Zone[_current], _ROOT_ZONE))
+      if (core.identical(Zone[_current$], _ROOT_ZONE))
         return dart.dinvokef(f, arg1, arg2);
       return _rootRunBinary(null, null, this, f, arg1, arg2);
     }
@@ -4876,10 +4876,10 @@ var async;
   });
   let _ROOT_ZONE = new _RootZone();
   // Function runZoned: (() → dynamic, {zoneValues: Map<dynamic, dynamic>, zoneSpecification: ZoneSpecification, onError: Function}) → dynamic
-  function runZoned(body, opt$) {
-    let zoneValues = opt$ && 'zoneValues' in opt$ ? opt$.zoneValues : null;
-    let zoneSpecification = opt$ && 'zoneSpecification' in opt$ ? opt$.zoneSpecification : null;
-    let onError = opt$ && 'onError' in opt$ ? opt$.onError : null;
+  function runZoned(body, opts) {
+    let zoneValues = opts && 'zoneValues' in opts ? opts.zoneValues : null;
+    let zoneSpecification = opts && 'zoneSpecification' in opts ? opts.zoneSpecification : null;
+    let onError = opts && 'onError' in opts ? opts.onError : null;
     let errorHandler = null;
     if (onError !== null) {
       errorHandler = (self, parent, zone, error, stackTrace) => {
diff --git a/pkg/dev_compiler/lib/runtime/dart/collection.js b/pkg/dev_compiler/lib/runtime/dart/collection.js
index a4e55a83d465..9b0eaadf94e9 100644
--- a/pkg/dev_compiler/lib/runtime/dart/collection.js
+++ b/pkg/dev_compiler/lib/runtime/dart/collection.js
@@ -28,10 +28,10 @@ var collection;
   }
   let HashMap$ = dart.generic(function(K, V) {
     class HashMap extends core.Object {
-      HashMap(opt$) {
-        let equals = opt$ && 'equals' in opt$ ? opt$.equals : null;
-        let hashCode = opt$ && 'hashCode' in opt$ ? opt$.hashCode : null;
-        let isValidKey = opt$ && 'isValidKey' in opt$ ? opt$.isValidKey : null;
+      HashMap(opts) {
+        let equals = opts && 'equals' in opts ? opts.equals : null;
+        let hashCode = opts && 'hashCode' in opts ? opts.hashCode : null;
+        let isValidKey = opts && 'isValidKey' in opts ? opts.isValidKey : null;
         if (isValidKey === null) {
           if (hashCode === null) {
             if (equals === null) {
@@ -66,9 +66,9 @@ var collection;
         });
         return result;
       }
-      HashMap$fromIterable(iterable, opt$) {
-        let key = opt$ && 'key' in opt$ ? opt$.key : null;
-        let value = opt$ && 'value' in opt$ ? opt$.value : null;
+      HashMap$fromIterable(iterable, opts) {
+        let key = opts && 'key' in opts ? opts.key : null;
+        let value = opts && 'value' in opts ? opts.value : null;
         let map = new HashMap();
         Maps._fillMapWithMappedIterable(map, iterable, key, value);
         return map;
@@ -158,15 +158,15 @@ var collection;
         }
         return result;
       }
-      toList(opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      toList(opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         let result = growable ? ((_) => {
           _.length = this.length;
           return _;
         }).bind(this)(new core.List()) : new core.List(this.length);
         let i = 0;
         for (let element of this)
-          result.set((($tmp) => i = dart.notNull($tmp) + 1, $tmp)(i), element);
+          result.set(((x) => i = dart.notNull(x$) + 1, x$)(i), element);
         return result;
       }
       map(f) {
@@ -275,8 +275,8 @@ var collection;
         } while (it.moveNext());
         return result;
       }
-      firstWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      firstWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         for (let element of this) {
           if (test(element))
             return element;
@@ -285,8 +285,8 @@ var collection;
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
-      lastWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      lastWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         let result = null;
         let foundMatching = false;
         for (let element of this) {
@@ -372,10 +372,10 @@ var collection;
   let _HashSetBase = _HashSetBase$(dart.dynamic);
   let HashSet$ = dart.generic(function(E) {
     class HashSet extends core.Object {
-      HashSet(opt$) {
-        let equals = opt$ && 'equals' in opt$ ? opt$.equals : null;
-        let hashCode = opt$ && 'hashCode' in opt$ ? opt$.hashCode : null;
-        let isValidKey = opt$ && 'isValidKey' in opt$ ? opt$.isValidKey : null;
+      HashSet(opts) {
+        let equals = opts && 'equals' in opts ? opts.equals : null;
+        let hashCode = opts && 'hashCode' in opts ? opts.hashCode : null;
+        let isValidKey = opts && 'isValidKey' in opts ? opts.isValidKey : null;
         if (isValidKey === null) {
           if (hashCode === null) {
             if (equals === null) {
@@ -488,8 +488,8 @@ var collection;
         }
         return false;
       }
-      toList(opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      toList(opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         return new core.List.from(this, {growable: growable});
       }
       toSet() {
@@ -549,8 +549,8 @@ var collection;
           throw _internal.IterableElementError.tooMany();
         return result;
       }
-      firstWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      firstWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         for (let element of this) {
           if (test(element))
             return element;
@@ -559,8 +559,8 @@ var collection;
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
-      lastWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      lastWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         let result = null;
         let foundMatching = false;
         for (let element of this) {
@@ -610,8 +610,8 @@ var collection;
     return IterableMixin;
   });
   let IterableMixin = IterableMixin$(dart.dynamic);
-  let _isToStringVisiting = Symbol('_isToStringVisiting');
-  let _iterablePartsToStrings = Symbol('_iterablePartsToStrings');
+  let _isToStringVisiting$ = Symbol('_isToStringVisiting');
+  let _iterablePartsToStrings$ = Symbol('_iterablePartsToStrings');
   let IterableBase$ = dart.generic(function(E) {
     class IterableBase extends core.Object {
       IterableBase() {
@@ -687,8 +687,8 @@ var collection;
         }
         return false;
       }
-      toList(opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      toList(opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         return new core.List.from(this, {growable: growable});
       }
       toSet() {
@@ -748,8 +748,8 @@ var collection;
           throw _internal.IterableElementError.tooMany();
         return result;
       }
-      firstWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      firstWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         for (let element of this) {
           if (test(element))
             return element;
@@ -758,8 +758,8 @@ var collection;
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
-      lastWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      lastWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         let result = null;
         let foundMatching = false;
         for (let element of this) {
@@ -849,14 +849,14 @@ var collection;
         buffer.write(rightDelimiter);
         return buffer.toString();
       }
-      static [_isToStringVisiting](o) {
+      static [_isToStringVisiting$](o) {
         for (let i = 0; dart.notNull(i) < dart.notNull(_toStringVisiting.length); i = dart.notNull(i) + 1) {
           if (core.identical(o, _toStringVisiting.get(i)))
             return true;
         }
         return false;
       }
-      static [_iterablePartsToStrings](iterable, parts) {
+      static [_iterablePartsToStrings$](iterable, parts) {
         let LENGTH_LIMIT = 80;
         let HEAD_COUNT = 3;
         let TAIL_COUNT = 2;
@@ -948,8 +948,8 @@ var collection;
   let _move = Symbol('_move');
   let HasNextIterator$ = dart.generic(function(E) {
     class HasNextIterator extends core.Object {
-      HasNextIterator($_iterator) {
-        this[_iterator] = $_iterator;
+      HasNextIterator(iterator$) {
+        this[_iterator] = iterator$;
         this[_state] = HasNextIterator._NOT_MOVED_YET;
       }
       get hasNext() {
@@ -981,10 +981,10 @@ var collection;
   let HasNextIterator = HasNextIterator$(dart.dynamic);
   let LinkedHashMap$ = dart.generic(function(K, V) {
     class LinkedHashMap extends core.Object {
-      LinkedHashMap(opt$) {
-        let equals = opt$ && 'equals' in opt$ ? opt$.equals : null;
-        let hashCode = opt$ && 'hashCode' in opt$ ? opt$.hashCode : null;
-        let isValidKey = opt$ && 'isValidKey' in opt$ ? opt$.isValidKey : null;
+      LinkedHashMap(opts) {
+        let equals = opts && 'equals' in opts ? opts.equals : null;
+        let hashCode = opts && 'hashCode' in opts ? opts.hashCode : null;
+        let isValidKey = opts && 'isValidKey' in opts ? opts.isValidKey : null;
         if (isValidKey === null) {
           if (hashCode === null) {
             if (equals === null) {
@@ -1019,9 +1019,9 @@ var collection;
         });
         return result;
       }
-      LinkedHashMap$fromIterable(iterable, opt$) {
-        let key = opt$ && 'key' in opt$ ? opt$.key : null;
-        let value = opt$ && 'value' in opt$ ? opt$.value : null;
+      LinkedHashMap$fromIterable(iterable, opts) {
+        let key = opts && 'key' in opts ? opts.key : null;
+        let value = opts && 'value' in opts ? opts.value : null;
         let map = new LinkedHashMap();
         Maps._fillMapWithMappedIterable(map, iterable, key, value);
         return map;
@@ -1049,10 +1049,10 @@ var collection;
   let LinkedHashMap = LinkedHashMap$(dart.dynamic, dart.dynamic);
   let LinkedHashSet$ = dart.generic(function(E) {
     class LinkedHashSet extends core.Object {
-      LinkedHashSet(opt$) {
-        let equals = opt$ && 'equals' in opt$ ? opt$.equals : null;
-        let hashCode = opt$ && 'hashCode' in opt$ ? opt$.hashCode : null;
-        let isValidKey = opt$ && 'isValidKey' in opt$ ? opt$.isValidKey : null;
+      LinkedHashSet(opts) {
+        let equals = opts && 'equals' in opts ? opts.equals : null;
+        let hashCode = opts && 'hashCode' in opts ? opts.hashCode : null;
+        let isValidKey = opts && 'isValidKey' in opts ? opts.isValidKey : null;
         if (isValidKey === null) {
           if (hashCode === null) {
             if (equals === null) {
@@ -1270,7 +1270,7 @@ var collection;
     return LinkedListEntry;
   });
   let LinkedListEntry = LinkedListEntry$(dart.dynamic);
-  let _filter = Symbol('_filter');
+  let _filter$ = Symbol('_filter');
   let ListMixin$ = dart.generic(function(E) {
     class ListMixin extends core.Object {
       get iterator() {
@@ -1344,8 +1344,8 @@ var collection;
         }
         return false;
       }
-      firstWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      firstWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         let length = this.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           let element = this.get(i);
@@ -1359,8 +1359,8 @@ var collection;
           return orElse();
         throw _internal.IterableElementError.noElement();
       }
-      lastWhere(test, opt$) {
-        let orElse = opt$ && 'orElse' in opt$ ? opt$.orElse : null;
+      lastWhere(test, opts) {
+        let orElse = opts && 'orElse' in opts ? opts.orElse : null;
         let length = this.length;
         for (let i = dart.notNull(length) - 1; dart.notNull(i) >= 0; i = dart.notNull(i) - 1) {
           let element = this.get(i);
@@ -1449,8 +1449,8 @@ var collection;
       takeWhile(test) {
         return new _internal.TakeWhileIterable(this, test);
       }
-      toList(opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      toList(opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         let result = null;
         if (growable) {
           result = ((_) => {
@@ -1473,11 +1473,11 @@ var collection;
         return result;
       }
       add(element) {
-        this.set((($tmp) => this.length = dart.notNull($tmp) + 1, $tmp).bind(this)(this.length), element);
+        this.set(((x) => this.length = dart.notNull(x$) + 1, x$).bind(this)(this.length), element);
       }
       addAll(iterable) {
         for (let element of iterable) {
-          this.set((($tmp) => this.length = dart.notNull($tmp) + 1, $tmp).bind(this)(this.length), element);
+          this.set(((x) => this.length = dart.notNull(x$) + 1, x$).bind(this)(this.length), element);
         }
       }
       remove(element) {
@@ -1496,7 +1496,7 @@ var collection;
       retainWhere(test) {
         _filter(this, test, true);
       }
-      static [_filter](source, test, retainMatching) {
+      static [_filter$](source, test, retainMatching) {
         let retained = new List.from([]);
         let length = source.length;
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
@@ -1707,7 +1707,7 @@ var collection;
           this.setRange(index, dart.notNull(index) + dart.notNull(iterable.length), iterable);
         } else {
           for (let element of iterable) {
-            this.set((($tmp) => index = dart.notNull($tmp) + 1, $tmp)(index), element);
+            this.set(((x) => index = dart.notNull(x$) + 1, x$)(index), element);
           }
         }
       }
@@ -1813,8 +1813,8 @@ var collection;
   let _map = Symbol('_map');
   let _MapBaseValueIterable$ = dart.generic(function(V) {
     class _MapBaseValueIterable extends IterableBase$(V) {
-      _MapBaseValueIterable($_map) {
-        this[_map] = $_map;
+      _MapBaseValueIterable(map$) {
+        this[_map] = map$;
         super.IterableBase();
       }
       get length() {
@@ -1925,8 +1925,8 @@ var collection;
     return UnmodifiableMapView;
   });
   let UnmodifiableMapView = UnmodifiableMapView$(dart.dynamic, dart.dynamic);
-  let _toStringVisiting = Symbol('_toStringVisiting');
-  let _id = Symbol('_id');
+  let _toStringVisiting$ = Symbol('_toStringVisiting');
+  let _id$ = Symbol('_id');
   let _fillMapWithMappedIterable = Symbol('_fillMapWithMappedIterable');
   let _fillMapWithIterables = Symbol('_fillMapWithIterables');
   class Maps extends core.Object {
@@ -1982,7 +1982,7 @@ var collection;
       }
       let result = new core.StringBuffer();
       try {
-        IterableBase[_toStringVisiting].add(m);
+        IterableBase[_toStringVisiting$].add(m);
         result.write('{');
         let first = true;
         m.forEach(((k, v) => {
@@ -1996,12 +1996,12 @@ var collection;
         }).bind(this));
         result.write('}');
       } finally {
-        dart.assert(core.identical(IterableBase[_toStringVisiting].last, m));
-        IterableBase[_toStringVisiting].removeLast();
+        dart.assert(core.identical(IterableBase[_toStringVisiting$].last, m));
+        IterableBase[_toStringVisiting$].removeLast();
       }
       return result.toString();
     }
-    static [_id](x) {
+    static [_id$](x) {
       return x;
     }
     static [_fillMapWithMappedIterable](map, iterable, key, value) {
@@ -2171,7 +2171,7 @@ var collection;
         }
         return false;
       }
-      [_filter](test, removeMatching) {
+      [_filter$](test, removeMatching) {
         let entry = this[_sentinel][_next];
         while (!dart.notNull(core.identical(entry, this[_sentinel]))) {
           let next = entry[_next];
@@ -2183,10 +2183,10 @@ var collection;
         }
       }
       removeWhere(test) {
-        this[_filter](test, true);
+        this[_filter$](test, true);
       }
       retainWhere(test) {
-        this[_filter](test, false);
+        this[_filter$](test, false);
       }
       get first() {
         return this[_sentinel][_next].element;
@@ -2268,8 +2268,8 @@ var collection;
   let _remove = Symbol('_remove');
   let _filterWhere = Symbol('_filterWhere');
   let _grow = Symbol('_grow');
-  let _isPowerOf2 = Symbol('_isPowerOf2');
-  let _nextPowerOf2 = Symbol('_nextPowerOf2');
+  let _isPowerOf2$ = Symbol('_isPowerOf2');
+  let _nextPowerOf2$ = Symbol('_nextPowerOf2');
   let ListQueue$ = dart.generic(function(E) {
     class ListQueue extends IterableBase$(E) {
       ListQueue(initialCapacity) {
@@ -2346,8 +2346,8 @@ var collection;
         core.RangeError.checkValidIndex(index, this);
         return this[_table].get(dart.notNull(this[_head]) + dart.notNull(index) & dart.notNull(this[_table].length) - 1);
       }
-      toList(opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      toList(opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         let list = null;
         if (growable) {
           list = ((_) => {
@@ -2463,10 +2463,10 @@ var collection;
         this[_table].set(this[_tail], null);
         return result;
       }
-      static [_isPowerOf2](number) {
+      static [_isPowerOf2$](number) {
         return (dart.notNull(number) & dart.notNull(number) - 1) === 0;
       }
-      static [_nextPowerOf2](number) {
+      static [_nextPowerOf2$](number) {
         dart.assert(dart.notNull(number) > 0);
         number = (dart.notNull(number) << 1) - 1;
         for (;;) {
@@ -2785,11 +2785,11 @@ var collection;
         });
         return result;
       }
-      SplayTreeMap$fromIterable(iterable, opt$) {
-        let key = opt$ && 'key' in opt$ ? opt$.key : null;
-        let value = opt$ && 'value' in opt$ ? opt$.value : null;
-        let compare = opt$ && 'compare' in opt$ ? opt$.compare : null;
-        let isValidKey = opt$ && 'isValidKey' in opt$ ? opt$.isValidKey : null;
+      SplayTreeMap$fromIterable(iterable, opts) {
+        let key = opts && 'key' in opts ? opts.key : null;
+        let value = opts && 'value' in opts ? opts.value : null;
+        let compare = opts && 'compare' in opts ? opts.compare : null;
+        let isValidKey = opts && 'isValidKey' in opts ? opts.isValidKey : null;
         let map = new SplayTreeMap(compare, isValidKey);
         Maps._fillMapWithMappedIterable(map, iterable, key, value);
         return map;
@@ -3046,8 +3046,8 @@ var collection;
   let _SplayTreeIterator = _SplayTreeIterator$(dart.dynamic);
   let _SplayTreeKeyIterable$ = dart.generic(function(K) {
     class _SplayTreeKeyIterable extends IterableBase$(K) {
-      _SplayTreeKeyIterable($_tree) {
-        this[_tree] = $_tree;
+      _SplayTreeKeyIterable(tree$) {
+        this[_tree] = tree$;
         super.IterableBase();
       }
       get length() {
@@ -3072,8 +3072,8 @@ var collection;
   let _SplayTreeKeyIterable = _SplayTreeKeyIterable$(dart.dynamic);
   let _SplayTreeValueIterable$ = dart.generic(function(K, V) {
     class _SplayTreeValueIterable extends IterableBase$(V) {
-      _SplayTreeValueIterable($_map) {
-        this[_map] = $_map;
+      _SplayTreeValueIterable(map$) {
+        this[_map] = map$;
         super.IterableBase();
       }
       get length() {
@@ -3301,13 +3301,13 @@ var collection;
   let _set = Symbol('_set');
   let _computeHashCode = Symbol('_computeHashCode');
   let _removeHashTableEntry = Symbol('_removeHashTableEntry');
-  let _isStringKey = Symbol('_isStringKey');
-  let _isNumericKey = Symbol('_isNumericKey');
-  let _hasTableEntry = Symbol('_hasTableEntry');
-  let _getTableEntry = Symbol('_getTableEntry');
-  let _setTableEntry = Symbol('_setTableEntry');
-  let _deleteTableEntry = Symbol('_deleteTableEntry');
-  let _newHashTable = Symbol('_newHashTable');
+  let _isStringKey$ = Symbol('_isStringKey');
+  let _isNumericKey$ = Symbol('_isNumericKey');
+  let _hasTableEntry$ = Symbol('_hasTableEntry');
+  let _getTableEntry$ = Symbol('_getTableEntry');
+  let _setTableEntry$ = Symbol('_setTableEntry');
+  let _deleteTableEntry$ = Symbol('_deleteTableEntry');
+  let _newHashTable$ = Symbol('_newHashTable');
   let _HashMap$ = dart.generic(function(K, V) {
     class _HashMap extends core.Object {
       _HashMap() {
@@ -3518,31 +3518,31 @@ var collection;
           return null;
         }
       }
-      static [_isStringKey](key) {
+      static [_isStringKey$](key) {
         return dart.notNull(typeof key == string) && dart.notNull(!dart.equals(key, '__proto__'));
       }
-      static [_isNumericKey](key) {
+      static [_isNumericKey$](key) {
         return dart.notNull(dart.is(key, core.num)) && (key & 0x3ffffff) === key;
       }
       [_computeHashCode](key) {
         return dart.dload(key, 'hashCode') & 0x3ffffff;
       }
-      static [_hasTableEntry](table, key) {
+      static [_hasTableEntry$](table, key) {
         let entry = table[key];
         return entry !== null;
       }
-      static [_getTableEntry](table, key) {
+      static [_getTableEntry$](table, key) {
         let entry = table[key];
         return entry === table ? null : entry;
       }
-      static [_setTableEntry](table, key, value) {
+      static [_setTableEntry$](table, key, value) {
         if (value === null) {
           table[key] = table;
         } else {
           table[key] = value;
         }
       }
-      static [_deleteTableEntry](table, key) {
+      static [_deleteTableEntry$](table, key) {
         delete table[key];
       }
       [_getBucket](table, key) {
@@ -3559,7 +3559,7 @@ var collection;
         }
         return -1;
       }
-      static [_newHashTable]() {
+      static [_newHashTable$]() {
         let table = Object.create(null);
         let temporaryKey = '<non-identifier-key>';
         _setTableEntry(table, temporaryKey, table);
@@ -3593,9 +3593,9 @@ var collection;
   let _hashCode = Symbol('_hashCode');
   let _CustomHashMap$ = dart.generic(function(K, V) {
     class _CustomHashMap extends _HashMap$(K, V) {
-      _CustomHashMap($_equals, $_hashCode, validKey) {
-        this[_equals] = $_equals;
-        this[_hashCode] = $_hashCode;
+      _CustomHashMap(equals$, hashCode$, validKey) {
+        this[_equals] = equals$;
+        this[_hashCode] = hashCode$;
         this[_validKey] = dart.as(validKey !== null ? validKey : (v) => dart.is(v, K), _Predicate);
         super._HashMap();
       }
@@ -3639,8 +3639,8 @@ var collection;
   let _CustomHashMap = _CustomHashMap$(dart.dynamic, dart.dynamic);
   let HashMapKeyIterable$ = dart.generic(function(E) {
     class HashMapKeyIterable extends IterableBase$(E) {
-      HashMapKeyIterable($_map) {
-        this[_map] = $_map;
+      HashMapKeyIterable(map$) {
+        this[_map] = map$;
         super.IterableBase();
       }
       get length() {
@@ -3671,9 +3671,9 @@ var collection;
   let _offset = Symbol('_offset');
   let HashMapKeyIterator$ = dart.generic(function(E) {
     class HashMapKeyIterator extends core.Object {
-      HashMapKeyIterator($_map, $_keys) {
-        this[_map] = $_map;
-        this[_keys] = $_keys;
+      HashMapKeyIterator(map$, keys$) {
+        this[_map] = map$;
+        this[_keys] = keys$;
         this[_offset] = 0;
         this[_current] = null;
       }
@@ -3923,23 +3923,23 @@ var collection;
         this[_length] = dart.notNull(this[_length]) - 1;
         this[_modified]();
       }
-      static [_isStringKey](key) {
+      static [_isStringKey$](key) {
         return dart.notNull(typeof key == string) && dart.notNull(!dart.equals(key, '__proto__'));
       }
-      static [_isNumericKey](key) {
+      static [_isNumericKey$](key) {
         return dart.notNull(dart.is(key, core.num)) && (key & 0x3ffffff) === key;
       }
       [_computeHashCode](key) {
         return dart.dload(key, 'hashCode') & 0x3ffffff;
       }
-      static [_getTableEntry](table, key) {
+      static [_getTableEntry$](table, key) {
         return table[key];
       }
-      static [_setTableEntry](table, key, value) {
+      static [_setTableEntry$](table, key, value) {
         dart.assert(value !== null);
         table[key] = value;
       }
-      static [_deleteTableEntry](table, key) {
+      static [_deleteTableEntry$](table, key) {
         delete table[key];
       }
       [_getBucket](table, key) {
@@ -3957,7 +3957,7 @@ var collection;
         }
         return -1;
       }
-      static [_newHashTable]() {
+      static [_newHashTable$]() {
         let table = Object.create(null);
         let temporaryKey = '<non-identifier-key>';
         _setTableEntry(table, temporaryKey, table);
@@ -3993,9 +3993,9 @@ var collection;
   let _LinkedIdentityHashMap = _LinkedIdentityHashMap$(dart.dynamic, dart.dynamic);
   let _LinkedCustomHashMap$ = dart.generic(function(K, V) {
     class _LinkedCustomHashMap extends _LinkedHashMap$(K, V) {
-      _LinkedCustomHashMap($_equals, $_hashCode, validKey) {
-        this[_equals] = $_equals;
-        this[_hashCode] = $_hashCode;
+      _LinkedCustomHashMap(equals$, hashCode$, validKey) {
+        this[_equals] = equals$;
+        this[_hashCode] = hashCode$;
         this[_validKey] = dart.as(validKey !== null ? validKey : (v) => dart.is(v, K), _Predicate);
         super._LinkedHashMap();
       }
@@ -4036,17 +4036,17 @@ var collection;
   });
   let _LinkedCustomHashMap = _LinkedCustomHashMap$(dart.dynamic, dart.dynamic);
   class LinkedHashMapCell extends core.Object {
-    LinkedHashMapCell($_key, $_value) {
-      this[_key] = $_key;
-      this[_value] = $_value;
+    LinkedHashMapCell(key$, value$) {
+      this[_key] = key$;
+      this[_value] = value$;
       this[_next] = null;
       this[_previous] = null;
     }
   }
   let LinkedHashMapKeyIterable$ = dart.generic(function(E) {
     class LinkedHashMapKeyIterable extends IterableBase$(E) {
-      LinkedHashMapKeyIterable($_map) {
-        this[_map] = $_map;
+      LinkedHashMapKeyIterable(map$) {
+        this[_map] = map$;
         super.IterableBase();
       }
       get length() {
@@ -4079,9 +4079,9 @@ var collection;
   let _cell = Symbol('_cell');
   let LinkedHashMapKeyIterator$ = dart.generic(function(E) {
     class LinkedHashMapKeyIterator extends core.Object {
-      LinkedHashMapKeyIterator($_map, $_modifications) {
-        this[_map] = $_map;
-        this[_modifications] = $_modifications;
+      LinkedHashMapKeyIterator(map$, modifications$) {
+        this[_map] = map$;
+        this[_modifications] = modifications$;
         this[_cell] = null;
         this[_current] = null;
         this[_cell] = dart.as(dart.dload(this[_map], '_first'), LinkedHashMapCell);
@@ -4109,8 +4109,8 @@ var collection;
   let _computeElements = Symbol('_computeElements');
   let _contains = Symbol('_contains');
   let _lookup = Symbol('_lookup');
-  let _isStringElement = Symbol('_isStringElement');
-  let _isNumericElement = Symbol('_isNumericElement');
+  let _isStringElement$ = Symbol('_isStringElement');
+  let _isNumericElement$ = Symbol('_isNumericElement');
   let _HashSet$ = dart.generic(function(E) {
     class _HashSet extends _HashSetBase$(E) {
       _HashSet() {
@@ -4296,24 +4296,24 @@ var collection;
           return false;
         }
       }
-      static [_isStringElement](element) {
+      static [_isStringElement$](element) {
         return dart.notNull(typeof element == string) && dart.notNull(!dart.equals(element, '__proto__'));
       }
-      static [_isNumericElement](element) {
+      static [_isNumericElement$](element) {
         return dart.notNull(dart.is(element, core.num)) && (element & 0x3ffffff) === element;
       }
       [_computeHashCode](element) {
         return dart.dload(element, 'hashCode') & 0x3ffffff;
       }
-      static [_hasTableEntry](table, key) {
+      static [_hasTableEntry$](table, key) {
         let entry = table[key];
         return entry !== null;
       }
-      static [_setTableEntry](table, key, value) {
+      static [_setTableEntry$](table, key, value) {
         dart.assert(value !== null);
         table[key] = value;
       }
-      static [_deleteTableEntry](table, key) {
+      static [_deleteTableEntry$](table, key) {
         delete table[key];
       }
       [_getBucket](table, element) {
@@ -4330,7 +4330,7 @@ var collection;
         }
         return -1;
       }
-      static [_newHashTable]() {
+      static [_newHashTable$]() {
         let table = Object.create(null);
         let temporaryKey = '<non-identifier-key>';
         _setTableEntry(table, temporaryKey, table);
@@ -4367,9 +4367,9 @@ var collection;
   let _hasher = Symbol('_hasher');
   let _CustomHashSet$ = dart.generic(function(E) {
     class _CustomHashSet extends _HashSet$(E) {
-      _CustomHashSet($_equality, $_hasher, validKey) {
-        this[_equality] = $_equality;
-        this[_hasher] = $_hasher;
+      _CustomHashSet(equality, hasher, validKey) {
+        this[_equality] = equality;
+        this[_hasher] = hasher;
         this[_validKey] = dart.as(validKey !== null ? validKey : (x) => dart.is(x, E), _Predicate);
         super._HashSet();
       }
@@ -4413,9 +4413,9 @@ var collection;
   let _CustomHashSet = _CustomHashSet$(dart.dynamic);
   let HashSetIterator$ = dart.generic(function(E) {
     class HashSetIterator extends core.Object {
-      HashSetIterator($_set, $_elements) {
-        this[_set] = $_set;
-        this[_elements] = $_elements;
+      HashSetIterator(set$, elements$) {
+        this[_set] = set$;
+        this[_elements] = elements$;
         this[_offset] = 0;
         this[_current] = null;
       }
@@ -4666,23 +4666,23 @@ var collection;
         this[_length] = dart.notNull(this[_length]) - 1;
         this[_modified]();
       }
-      static [_isStringElement](element) {
+      static [_isStringElement$](element) {
         return dart.notNull(typeof element == string) && dart.notNull(!dart.equals(element, '__proto__'));
       }
-      static [_isNumericElement](element) {
+      static [_isNumericElement$](element) {
         return dart.notNull(dart.is(element, core.num)) && (element & 0x3ffffff) === element;
       }
       [_computeHashCode](element) {
         return dart.dload(element, 'hashCode') & 0x3ffffff;
       }
-      static [_getTableEntry](table, key) {
+      static [_getTableEntry$](table, key) {
         return table[key];
       }
-      static [_setTableEntry](table, key, value) {
+      static [_setTableEntry$](table, key, value) {
         dart.assert(value !== null);
         table[key] = value;
       }
-      static [_deleteTableEntry](table, key) {
+      static [_deleteTableEntry$](table, key) {
         delete table[key];
       }
       [_getBucket](table, element) {
@@ -4700,7 +4700,7 @@ var collection;
         }
         return -1;
       }
-      static [_newHashTable]() {
+      static [_newHashTable$]() {
         let table = Object.create(null);
         let temporaryKey = '<non-identifier-key>';
         _setTableEntry(table, temporaryKey, table);
@@ -4736,9 +4736,9 @@ var collection;
   let _LinkedIdentityHashSet = _LinkedIdentityHashSet$(dart.dynamic);
   let _LinkedCustomHashSet$ = dart.generic(function(E) {
     class _LinkedCustomHashSet extends _LinkedHashSet$(E) {
-      _LinkedCustomHashSet($_equality, $_hasher, validKey) {
-        this[_equality] = $_equality;
-        this[_hasher] = $_hasher;
+      _LinkedCustomHashSet(equality, hasher, validKey) {
+        this[_equality] = equality;
+        this[_hasher] = hasher;
         this[_validKey] = dart.as(validKey !== null ? validKey : (x) => dart.is(x, E), _Predicate);
         super._LinkedHashSet();
       }
@@ -4796,17 +4796,17 @@ var collection;
   });
   let _LinkedCustomHashSet = _LinkedCustomHashSet$(dart.dynamic);
   class LinkedHashSetCell extends core.Object {
-    LinkedHashSetCell($_element) {
-      this[_element] = $_element;
+    LinkedHashSetCell(element$) {
+      this[_element] = element$;
       this[_next] = null;
       this[_previous] = null;
     }
   }
   let LinkedHashSetIterator$ = dart.generic(function(E) {
     class LinkedHashSetIterator extends core.Object {
-      LinkedHashSetIterator($_set, $_modifications) {
-        this[_set] = $_set;
-        this[_modifications] = $_modifications;
+      LinkedHashSetIterator(set$, modifications$) {
+        this[_set] = set$;
+        this[_modifications] = modifications$;
         this[_cell] = null;
         this[_current] = null;
         this[_cell] = dart.as(dart.dload(this[_set], '_first'), LinkedHashSetCell);
diff --git a/pkg/dev_compiler/lib/runtime/dart/convert.js b/pkg/dev_compiler/lib/runtime/dart/convert.js
index f43fec837b5f..d932ca971b8f 100644
--- a/pkg/dev_compiler/lib/runtime/dart/convert.js
+++ b/pkg/dev_compiler/lib/runtime/dart/convert.js
@@ -45,16 +45,16 @@ var convert;
     set _nameToEncoding(_) {}
   });
   class AsciiCodec extends Encoding {
-    AsciiCodec(opt$) {
-      let allowInvalid = opt$ && 'allowInvalid' in opt$ ? opt$.allowInvalid : false;
+    AsciiCodec(opts) {
+      let allowInvalid = opts && 'allowInvalid' in opts ? opts.allowInvalid : false;
       this[_allowInvalid] = allowInvalid;
       super.Encoding();
     }
     get name() {
       return "us-ascii";
     }
-    decode(bytes, opt$) {
-      let allowInvalid = opt$ && 'allowInvalid' in opt$ ? opt$.allowInvalid : null;
+    decode(bytes, opts) {
+      let allowInvalid = opts && 'allowInvalid' in opts ? opts.allowInvalid : null;
       if (allowInvalid === null)
         allowInvalid = this[_allowInvalid];
       if (allowInvalid) {
@@ -89,8 +89,8 @@ var convert;
   });
   let Converter = Converter$(dart.dynamic, dart.dynamic);
   class _UnicodeSubsetEncoder extends Converter$(core.String, core.List$(core.int)) {
-    _UnicodeSubsetEncoder($_subsetMask) {
-      this[_subsetMask] = $_subsetMask;
+    _UnicodeSubsetEncoder(subsetMask) {
+      this[_subsetMask] = subsetMask;
       super.Converter();
     }
     convert(string, start, end) {
@@ -143,9 +143,9 @@ var convert;
   class StringConversionSinkBase extends StringConversionSinkMixin {
   }
   class _UnicodeSubsetEncoderSink extends StringConversionSinkBase {
-    _UnicodeSubsetEncoderSink($_subsetMask, $_sink) {
-      this[_subsetMask] = $_subsetMask;
-      this[_sink] = $_sink;
+    _UnicodeSubsetEncoderSink(subsetMask, sink$) {
+      this[_subsetMask] = subsetMask;
+      this[_sink] = sink$;
       super.StringConversionSinkBase();
     }
     close() {
@@ -167,9 +167,9 @@ var convert;
   }
   let _convertInvalid = Symbol('_convertInvalid');
   class _UnicodeSubsetDecoder extends Converter$(core.List$(core.int), core.String) {
-    _UnicodeSubsetDecoder($_allowInvalid, $_subsetMask) {
-      this[_allowInvalid] = $_allowInvalid;
-      this[_subsetMask] = $_subsetMask;
+    _UnicodeSubsetDecoder(allowInvalid$, subsetMask) {
+      this[_allowInvalid] = allowInvalid$;
+      this[_subsetMask] = subsetMask;
       super.Converter();
     }
     convert(bytes, start, end) {
@@ -208,8 +208,8 @@ var convert;
     }
   }
   class AsciiDecoder extends _UnicodeSubsetDecoder {
-    AsciiDecoder(opt$) {
-      let allowInvalid = opt$ && 'allowInvalid' in opt$ ? opt$.allowInvalid : false;
+    AsciiDecoder(opts) {
+      let allowInvalid = opts && 'allowInvalid' in opts ? opts.allowInvalid : false;
       super._UnicodeSubsetDecoder(allowInvalid, _ASCII_MASK);
     }
     startChunkedConversion(sink) {
@@ -260,8 +260,8 @@ var convert;
     }
   }
   class _ErrorHandlingAsciiDecoderSink extends ByteConversionSinkBase {
-    _ErrorHandlingAsciiDecoderSink($_utf8Sink) {
-      this[_utf8Sink] = $_utf8Sink;
+    _ErrorHandlingAsciiDecoderSink(utf8Sink) {
+      this[_utf8Sink] = utf8Sink;
       super.ByteConversionSinkBase();
     }
     close() {
@@ -288,8 +288,8 @@ var convert;
     }
   }
   class _SimpleAsciiDecoderSink extends ByteConversionSinkBase {
-    _SimpleAsciiDecoderSink($_sink) {
-      this[_sink] = $_sink;
+    _SimpleAsciiDecoderSink(sink$) {
+      this[_sink] = sink$;
       super.ByteConversionSinkBase();
     }
     close() {
@@ -317,8 +317,8 @@ var convert;
     }
   }
   class _ByteAdapterSink extends ByteConversionSinkBase {
-    _ByteAdapterSink($_sink) {
-      this[_sink] = $_sink;
+    _ByteAdapterSink(sink$) {
+      this[_sink] = sink$;
       super.ByteConversionSinkBase();
     }
     add(chunk) {
@@ -331,7 +331,7 @@ var convert;
   let _buffer = Symbol('_buffer');
   let _callback = Symbol('_callback');
   let _bufferIndex = Symbol('_bufferIndex');
-  let _roundToPowerOf2 = Symbol('_roundToPowerOf2');
+  let _roundToPowerOf2$ = Symbol('_roundToPowerOf2');
   class _ByteCallbackSink extends ByteConversionSinkBase {
     _ByteCallbackSink(callback) {
       this[_buffer] = new typed_data.Uint8List(_ByteCallbackSink._INITIAL_BUFFER_SIZE);
@@ -351,7 +351,7 @@ var convert;
       this[_buffer].setRange(this[_bufferIndex], dart.notNull(this[_bufferIndex]) + dart.notNull(chunk.length), chunk);
       this[_bufferIndex] = chunk.length;
     }
-    static [_roundToPowerOf2](v) {
+    static [_roundToPowerOf2$](v) {
       dart.assert(dart.notNull(v) > 0);
       v = dart.notNull(v) - 1;
       v = dart.notNull(v) >> 1;
@@ -370,9 +370,9 @@ var convert;
   let _accumulated = Symbol('_accumulated');
   let _SimpleCallbackSink$ = dart.generic(function(T) {
     class _SimpleCallbackSink extends ChunkedConversionSink$(T) {
-      _SimpleCallbackSink($_callback) {
+      _SimpleCallbackSink(callback$) {
         this[_accumulated] = new List.from([]);
-        this[_callback] = $_callback;
+        this[_callback] = callback$;
         super.ChunkedConversionSink();
       }
       add(chunk) {
@@ -387,8 +387,8 @@ var convert;
   let _SimpleCallbackSink = _SimpleCallbackSink$(dart.dynamic);
   let _EventSinkAdapter$ = dart.generic(function(T) {
     class _EventSinkAdapter extends core.Object {
-      _EventSinkAdapter($_sink) {
-        this[_sink] = $_sink;
+      _EventSinkAdapter(sink$) {
+        this[_sink] = sink$;
       }
       add(data) {
         return this[_sink].add(data);
@@ -433,9 +433,9 @@ var convert;
       get decoder() {
         return dart.as(this[_second].decoder.fuse(this[_first].decoder), Converter$(T, S));
       }
-      _FusedCodec($_first, $_second) {
-        this[_first] = $_first;
-        this[_second] = $_second;
+      _FusedCodec(first$, second) {
+        this[_first] = first$;
+        this[_second] = second;
         super.Codec();
       }
     }
@@ -464,9 +464,9 @@ var convert;
   let _InvertedCodec = _InvertedCodec$(dart.dynamic, dart.dynamic);
   let _FusedConverter$ = dart.generic(function(S, M, T) {
     class _FusedConverter extends Converter$(S, T) {
-      _FusedConverter($_first, $_second) {
-        this[_first] = $_first;
-        this[_second] = $_second;
+      _FusedConverter(first$, second) {
+        this[_first] = first$;
+        this[_second] = second;
         super.Converter();
       }
       convert(input) {
@@ -482,8 +482,8 @@ var convert;
   let HTML_ESCAPE = new HtmlEscape();
   let _name = Symbol('_name');
   class HtmlEscapeMode extends core.Object {
-    HtmlEscapeMode$_($_name, escapeLtGt, escapeQuot, escapeApos, escapeSlash) {
-      this[_name] = $_name;
+    HtmlEscapeMode$_(name$, escapeLtGt, escapeQuot, escapeApos, escapeSlash) {
+      this[_name] = name$;
       this.escapeLtGt = escapeLtGt;
       this.escapeQuot = escapeQuot;
       this.escapeApos = escapeApos;
@@ -561,9 +561,9 @@ var convert;
   }
   let _escape = Symbol('_escape');
   class _HtmlEscapeSink extends StringConversionSinkBase {
-    _HtmlEscapeSink($_escape, $_sink) {
-      this[_escape] = $_escape;
-      this[_sink] = $_sink;
+    _HtmlEscapeSink(escape, sink$) {
+      this[_escape] = escape;
+      this[_sink] = sink$;
       super.StringConversionSinkBase();
     }
     addSlice(chunk, start, end, isLast) {
@@ -581,8 +581,8 @@ var convert;
     }
   }
   class JsonUnsupportedObjectError extends core.Error {
-    JsonUnsupportedObjectError(unsupportedObject, opt$) {
-      let cause = opt$ && 'cause' in opt$ ? opt$.cause : null;
+    JsonUnsupportedObjectError(unsupportedObject, opts) {
+      let cause = opts && 'cause' in opts ? opts.cause : null;
       this.unsupportedObject = unsupportedObject;
       this.cause = cause;
       super.Error();
@@ -605,38 +605,38 @@ var convert;
   }
   let JSON = new JsonCodec();
   let _reviver = Symbol('_reviver');
-  let _toEncodable = Symbol('_toEncodable');
+  let _toEncodable$ = Symbol('_toEncodable');
   class JsonCodec extends Codec$(core.Object, core.String) {
-    JsonCodec(opt$) {
-      let reviver = opt$ && 'reviver' in opt$ ? opt$.reviver : null;
-      let toEncodable = opt$ && 'toEncodable' in opt$ ? opt$.toEncodable : null;
+    JsonCodec(opts) {
+      let reviver = opts && 'reviver' in opts ? opts.reviver : null;
+      let toEncodable = opts && 'toEncodable' in opts ? opts.toEncodable : null;
       this[_reviver] = reviver;
-      this[_toEncodable] = toEncodable;
+      this[_toEncodable$] = toEncodable;
       super.Codec();
     }
     JsonCodec$withReviver(reviver) {
       this.JsonCodec({reviver: reviver});
     }
-    decode(source, opt$) {
-      let reviver = opt$ && 'reviver' in opt$ ? opt$.reviver : null;
+    decode(source, opts) {
+      let reviver = opts && 'reviver' in opts ? opts.reviver : null;
       if (reviver === null)
         reviver = this[_reviver];
       if (reviver === null)
         return this.decoder.convert(source);
       return new JsonDecoder(reviver).convert(source);
     }
-    encode(value, opt$) {
-      let toEncodable = opt$ && 'toEncodable' in opt$ ? opt$.toEncodable : null;
+    encode(value, opts) {
+      let toEncodable = opts && 'toEncodable' in opts ? opts.toEncodable : null;
       if (toEncodable === null)
-        toEncodable = this[_toEncodable];
+        toEncodable = this[_toEncodable$];
       if (toEncodable === null)
         return this.encoder.convert(value);
       return new JsonEncoder(dart.closureWrap(toEncodable, "(Object) → Object")).convert(value);
     }
     get encoder() {
-      if (this[_toEncodable] === null)
+      if (this[_toEncodable$] === null)
         return new JsonEncoder();
-      return new JsonEncoder(dart.closureWrap(this[_toEncodable], "(Object) → Object"));
+      return new JsonEncoder(dart.closureWrap(this[_toEncodable$], "(Object) → Object"));
     }
     get decoder() {
       if (this[_reviver] === null)
@@ -650,33 +650,33 @@ var convert;
       if (toEncodable === void 0)
         toEncodable = null;
       this.indent = null;
-      this[_toEncodable] = toEncodable;
+      this[_toEncodable$] = toEncodable;
       super.Converter();
     }
     JsonEncoder$withIndent(indent, toEncodable) {
       if (toEncodable === void 0)
         toEncodable = null;
       this.indent = indent;
-      this[_toEncodable] = toEncodable;
+      this[_toEncodable$] = toEncodable;
       super.Converter();
     }
     convert(object) {
-      return _JsonStringStringifier.stringify(object, dart.as(this[_toEncodable], dart.throw_("Unimplemented type (dynamic) → dynamic")), this.indent);
+      return _JsonStringStringifier.stringify(object, dart.as(this[_toEncodable$], dart.throw_("Unimplemented type (dynamic) → dynamic")), this.indent);
     }
     startChunkedConversion(sink) {
       if (!dart.is(sink, StringConversionSink)) {
         sink = new StringConversionSink.from(sink);
       } else if (dart.is(sink, _Utf8EncoderSink)) {
-        return new _JsonUtf8EncoderSink(sink[_sink], this[_toEncodable], JsonUtf8Encoder._utf8Encode(this.indent), JsonUtf8Encoder.DEFAULT_BUFFER_SIZE);
+        return new _JsonUtf8EncoderSink(sink[_sink], this[_toEncodable$], JsonUtf8Encoder._utf8Encode(this.indent), JsonUtf8Encoder.DEFAULT_BUFFER_SIZE);
       }
-      return new _JsonEncoderSink(dart.as(sink, StringConversionSink), this[_toEncodable], this.indent);
+      return new _JsonEncoderSink(dart.as(sink, StringConversionSink), this[_toEncodable$], this.indent);
     }
     bind(stream) {
       return dart.as(super.bind(stream), async.Stream$(core.String));
     }
     fuse(other) {
       if (dart.is(other, Utf8Encoder)) {
-        return new JsonUtf8Encoder(this.indent, dart.as(this[_toEncodable], dart.throw_("Unimplemented type (Object) → dynamic")));
+        return new JsonUtf8Encoder(this.indent, dart.as(this[_toEncodable$], dart.throw_("Unimplemented type (Object) → dynamic")));
       }
       return super.fuse(other);
     }
@@ -684,7 +684,7 @@ var convert;
   dart.defineNamedConstructor(JsonEncoder, 'withIndent');
   let _indent = Symbol('_indent');
   let _bufferSize = Symbol('_bufferSize');
-  let _utf8Encode = Symbol('_utf8Encode');
+  let _utf8Encode$ = Symbol('_utf8Encode');
   class JsonUtf8Encoder extends Converter$(core.Object, core.List$(core.int)) {
     JsonUtf8Encoder(indent, toEncodable, bufferSize) {
       if (indent === void 0)
@@ -694,11 +694,11 @@ var convert;
       if (bufferSize === void 0)
         bufferSize = JsonUtf8Encoder.DEFAULT_BUFFER_SIZE;
       this[_indent] = _utf8Encode(indent);
-      this[_toEncodable] = toEncodable;
+      this[_toEncodable$] = toEncodable;
       this[_bufferSize] = bufferSize;
       super.Converter();
     }
-    static [_utf8Encode](string) {
+    static [_utf8Encode$](string) {
       if (string === null)
         return null;
       if (string.isEmpty)
@@ -722,7 +722,7 @@ var convert;
         }
         bytes.add(chunk);
       }
-      _JsonUtf8Stringifier.stringify(object, this[_indent], dart.as(this[_toEncodable], dart.throw_("Unimplemented type (Object) → dynamic")), this[_bufferSize], addChunk);
+      _JsonUtf8Stringifier.stringify(object, this[_indent], dart.as(this[_toEncodable$], dart.throw_("Unimplemented type (Object) → dynamic")), this[_bufferSize], addChunk);
       if (bytes.length === 1)
         return bytes.get(0);
       let length = 0;
@@ -745,7 +745,7 @@ var convert;
       } else {
         byteSink = new ByteConversionSink.from(sink);
       }
-      return new _JsonUtf8EncoderSink(byteSink, this[_toEncodable], this[_indent], this[_bufferSize]);
+      return new _JsonUtf8EncoderSink(byteSink, this[_toEncodable$], this[_indent], this[_bufferSize]);
     }
     bind(stream) {
       return dart.as(super.bind(stream), async.Stream$(core.List$(core.int)));
@@ -757,10 +757,10 @@ var convert;
   JsonUtf8Encoder.DEFAULT_BUFFER_SIZE = 256;
   let _isDone = Symbol('_isDone');
   class _JsonEncoderSink extends ChunkedConversionSink$(core.Object) {
-    _JsonEncoderSink($_sink, $_toEncodable, $_indent) {
-      this[_sink] = $_sink;
-      this[_toEncodable] = $_toEncodable;
-      this[_indent] = $_indent;
+    _JsonEncoderSink(sink$, toEncodable$, indent$) {
+      this[_sink] = sink$;
+      this[_toEncodable$] = toEncodable$;
+      this[_indent] = indent$;
       this[_isDone] = false;
       super.ChunkedConversionSink();
     }
@@ -770,18 +770,18 @@ var convert;
       }
       this[_isDone] = true;
       let stringSink = this[_sink].asStringSink();
-      _JsonStringStringifier.printOn(o, stringSink, dart.as(this[_toEncodable], dart.throw_("Unimplemented type (dynamic) → dynamic")), this[_indent]);
+      _JsonStringStringifier.printOn(o, stringSink, dart.as(this[_toEncodable$], dart.throw_("Unimplemented type (dynamic) → dynamic")), this[_indent]);
       stringSink.close();
     }
     close() {}
   }
   let _addChunk = Symbol('_addChunk');
   class _JsonUtf8EncoderSink extends ChunkedConversionSink$(core.Object) {
-    _JsonUtf8EncoderSink($_sink, $_toEncodable, $_indent, $_bufferSize) {
-      this[_sink] = $_sink;
-      this[_toEncodable] = $_toEncodable;
-      this[_indent] = $_indent;
-      this[_bufferSize] = $_bufferSize;
+    _JsonUtf8EncoderSink(sink$, toEncodable$, indent$, bufferSize$) {
+      this[_sink] = sink$;
+      this[_toEncodable$] = toEncodable$;
+      this[_indent] = indent$;
+      this[_bufferSize] = bufferSize$;
       this[_isDone] = false;
       super.ChunkedConversionSink();
     }
@@ -793,7 +793,7 @@ var convert;
         throw new core.StateError("Only one call to add allowed");
       }
       this[_isDone] = true;
-      _JsonUtf8Stringifier.stringify(object, this[_indent], dart.as(this[_toEncodable], dart.throw_("Unimplemented type (Object) → dynamic")), this[_bufferSize], this[_addChunk]);
+      _JsonUtf8Stringifier.stringify(object, this[_indent], dart.as(this[_toEncodable$], dart.throw_("Unimplemented type (Object) → dynamic")), this[_bufferSize], this[_addChunk]);
       this[_sink].close();
     }
     close() {
@@ -847,7 +847,7 @@ var convert;
   class _JsonStringifier extends core.Object {
     _JsonStringifier(_toEncodable) {
       this[_seen] = new core.List();
-      this[_toEncodable] = dart.as(_toEncodable !== null ? _toEncodable : _defaultToEncodable, core.Function);
+      this[_toEncodable$] = dart.as(_toEncodable !== null ? _toEncodable : _defaultToEncodable, core.Function);
     }
     static hexDigit(x) {
       return dart.notNull(x) < 10 ? 48 + dart.notNull(x) : 87 + dart.notNull(x);
@@ -920,7 +920,7 @@ var convert;
         return;
       this[_checkCycle](object);
       try {
-        let customJson = dart.dinvokef(this[_toEncodable], object);
+        let customJson = dart.dinvokef(this[_toEncodable$], object);
         if (!dart.notNull(this.writeJsonValue(customJson))) {
           throw new JsonUnsupportedObjectError(object);
         }
@@ -1052,8 +1052,8 @@ var convert;
     }
   }
   class _JsonStringStringifier extends _JsonStringifier {
-    _JsonStringStringifier($_sink, _toEncodable) {
-      this[_sink] = $_sink;
+    _JsonStringStringifier(sink$, _toEncodable) {
+      this[_sink] = sink$;
       super._JsonStringifier(dart.as(_toEncodable, dart.throw_("Unimplemented type (Object) → Object")));
     }
     static stringify(object, toEncodable, indent) {
@@ -1084,8 +1084,8 @@ var convert;
     }
   }
   class _JsonStringStringifierPretty extends dart.mixin(_JsonStringStringifier, _JsonPrettyPrintMixin) {
-    _JsonStringStringifierPretty(sink, toEncodable, $_indent) {
-      this[_indent] = $_indent;
+    _JsonStringStringifierPretty(sink, toEncodable, indent$) {
+      this[_indent] = indent$;
       super._JsonStringStringifier(sink, toEncodable);
     }
     writeIndentation(count) {
@@ -1185,7 +1185,7 @@ var convert;
         this.buffer = new typed_data.Uint8List(this.bufferSize);
         this.index = 0;
       }
-      this.buffer.set((($tmp) => this.index = dart.notNull($tmp) + 1, $tmp).bind(this)(this.index), byte);
+      this.buffer.set(((x) => this.index = dart.notNull(x$) + 1, x$).bind(this)(this.index), byte);
     }
   }
   class _JsonUtf8StringifierPretty extends dart.mixin(_JsonUtf8Stringifier, _JsonPrettyPrintMixin) {
@@ -1221,16 +1221,16 @@ var convert;
   let LATIN1 = new Latin1Codec();
   let _LATIN1_MASK = 255;
   class Latin1Codec extends Encoding {
-    Latin1Codec(opt$) {
-      let allowInvalid = opt$ && 'allowInvalid' in opt$ ? opt$.allowInvalid : false;
+    Latin1Codec(opts) {
+      let allowInvalid = opts && 'allowInvalid' in opts ? opts.allowInvalid : false;
       this[_allowInvalid] = allowInvalid;
       super.Encoding();
     }
     get name() {
       return "iso-8859-1";
     }
-    decode(bytes, opt$) {
-      let allowInvalid = opt$ && 'allowInvalid' in opt$ ? opt$.allowInvalid : null;
+    decode(bytes, opts) {
+      let allowInvalid = opts && 'allowInvalid' in opts ? opts.allowInvalid : null;
       if (allowInvalid === null)
         allowInvalid = this[_allowInvalid];
       if (allowInvalid) {
@@ -1252,8 +1252,8 @@ var convert;
     }
   }
   class Latin1Decoder extends _UnicodeSubsetDecoder {
-    Latin1Decoder(opt$) {
-      let allowInvalid = opt$ && 'allowInvalid' in opt$ ? opt$.allowInvalid : false;
+    Latin1Decoder(opts) {
+      let allowInvalid = opts && 'allowInvalid' in opts ? opts.allowInvalid : false;
       super._UnicodeSubsetDecoder(allowInvalid, _LATIN1_MASK);
     }
     startChunkedConversion(sink) {
@@ -1270,8 +1270,8 @@ var convert;
   }
   let _addSliceToSink = Symbol('_addSliceToSink');
   class _Latin1DecoderSink extends ByteConversionSinkBase {
-    _Latin1DecoderSink($_sink) {
-      this[_sink] = $_sink;
+    _Latin1DecoderSink(sink$) {
+      this[_sink] = sink$;
       super.ByteConversionSinkBase();
     }
     close() {
@@ -1341,10 +1341,10 @@ var convert;
     }
   }
   let _carry = Symbol('_carry');
-  let _addSlice = Symbol('_addSlice');
+  let _addSlice$ = Symbol('_addSlice');
   class _LineSplitterSink extends StringConversionSinkBase {
-    _LineSplitterSink($_sink) {
-      this[_sink] = $_sink;
+    _LineSplitterSink(sink$) {
+      this[_sink] = sink$;
       this[_carry] = null;
       super.StringConversionSinkBase();
     }
@@ -1362,7 +1362,7 @@ var convert;
     close() {
       this.addSlice('', 0, 0, true);
     }
-    static [_addSlice](chunk, start, end, isLast, adder) {
+    static [_addSlice$](chunk, start, end, isLast, adder) {
       let pos = start;
       while (dart.notNull(pos) < dart.notNull(end)) {
         let skip = 0;
@@ -1423,9 +1423,9 @@ var convert;
   }
   dart.defineNamedConstructor(ClosableStringSink, 'fromStringSink');
   class _ClosableStringSink extends core.Object {
-    _ClosableStringSink($_sink, $_callback) {
-      this[_sink] = $_sink;
-      this[_callback] = $_callback;
+    _ClosableStringSink(sink$, callback$) {
+      this[_sink] = sink$;
+      this[_callback] = callback$;
     }
     close() {
       return this[_callback]();
@@ -1449,8 +1449,8 @@ var convert;
   }
   let _flush = Symbol('_flush');
   class _StringConversionSinkAsStringSinkAdapter extends core.Object {
-    _StringConversionSinkAsStringSinkAdapter($_chunkedSink) {
-      this[_chunkedSink] = $_chunkedSink;
+    _StringConversionSinkAsStringSinkAdapter(chunkedSink) {
+      this[_chunkedSink] = chunkedSink;
       this[_buffer] = new core.StringBuffer();
     }
     close() {
@@ -1505,8 +1505,8 @@ var convert;
   _StringConversionSinkAsStringSinkAdapter._MIN_STRING_SIZE = 16;
   let _stringSink = Symbol('_stringSink');
   class _StringSinkConversionSink extends StringConversionSinkBase {
-    _StringSinkConversionSink($_stringSink) {
-      this[_stringSink] = $_stringSink;
+    _StringSinkConversionSink(stringSink$) {
+      this[_stringSink] = stringSink$;
       super.StringConversionSinkBase();
     }
     close() {}
@@ -1532,8 +1532,8 @@ var convert;
     }
   }
   class _StringCallbackSink extends _StringSinkConversionSink {
-    _StringCallbackSink($_callback) {
-      this[_callback] = $_callback;
+    _StringCallbackSink(callback$) {
+      this[_callback] = callback$;
       super._StringSinkConversionSink(new core.StringBuffer());
     }
     close() {
@@ -1547,8 +1547,8 @@ var convert;
     }
   }
   class _StringAdapterSink extends StringConversionSinkBase {
-    _StringAdapterSink($_sink) {
-      this[_sink] = $_sink;
+    _StringAdapterSink(sink$) {
+      this[_sink] = sink$;
       super.StringConversionSinkBase();
     }
     add(str) {
@@ -1569,8 +1569,8 @@ var convert;
   }
   let _decoder = Symbol('_decoder');
   class _Utf8StringSinkAdapter extends ByteConversionSink {
-    _Utf8StringSinkAdapter($_sink, stringSink, allowMalformed) {
-      this[_sink] = $_sink;
+    _Utf8StringSinkAdapter(sink$, stringSink, allowMalformed) {
+      this[_sink] = sink$;
       this[_decoder] = new _Utf8Decoder(stringSink, allowMalformed);
       super.ByteConversionSink();
     }
@@ -1593,8 +1593,8 @@ var convert;
     _Utf8ConversionSink(sink, allowMalformed) {
       this[_Utf8ConversionSink$_](sink, new core.StringBuffer(), allowMalformed);
     }
-    _Utf8ConversionSink$_($_chunkedSink, stringBuffer, allowMalformed) {
-      this[_chunkedSink] = $_chunkedSink;
+    _Utf8ConversionSink$_(chunkedSink, stringBuffer, allowMalformed) {
+      this[_chunkedSink] = chunkedSink;
       this[_decoder] = new _Utf8Decoder(stringBuffer, allowMalformed);
       this[_buffer] = stringBuffer;
       super.ByteConversionSink();
@@ -1630,16 +1630,16 @@ var convert;
   let UTF8 = new Utf8Codec();
   let _allowMalformed = Symbol('_allowMalformed');
   class Utf8Codec extends Encoding {
-    Utf8Codec(opt$) {
-      let allowMalformed = opt$ && 'allowMalformed' in opt$ ? opt$.allowMalformed : false;
+    Utf8Codec(opts) {
+      let allowMalformed = opts && 'allowMalformed' in opts ? opts.allowMalformed : false;
       this[_allowMalformed] = allowMalformed;
       super.Encoding();
     }
     get name() {
       return "utf-8";
     }
-    decode(codeUnits, opt$) {
-      let allowMalformed = opt$ && 'allowMalformed' in opt$ ? opt$.allowMalformed : null;
+    decode(codeUnits, opts) {
+      let allowMalformed = opts && 'allowMalformed' in opts ? opts.allowMalformed : null;
       if (allowMalformed === null)
         allowMalformed = this[_allowMalformed];
       return new Utf8Decoder({allowMalformed: allowMalformed}).convert(codeUnits);
@@ -1689,7 +1689,7 @@ var convert;
     }
   }
   let _Utf8Encoder$withBufferSize = Symbol('_Utf8Encoder$withBufferSize');
-  let _createBuffer = Symbol('_createBuffer');
+  let _createBuffer$ = Symbol('_createBuffer');
   let _writeSurrogate = Symbol('_writeSurrogate');
   let _fillBuffer = Symbol('_fillBuffer');
   class _Utf8Encoder extends core.Object {
@@ -1701,7 +1701,7 @@ var convert;
       this[_carry] = 0;
       this[_bufferIndex] = 0;
     }
-    static [_createBuffer](size) {
+    static [_createBuffer$](size) {
       return new typed_data.Uint8List(size);
     }
     [_writeSurrogate](leadingSurrogate, nextCodeUnit) {
@@ -1709,15 +1709,15 @@ var convert;
         let rune = _combineSurrogatePair(leadingSurrogate, nextCodeUnit);
         dart.assert(dart.notNull(rune) > dart.notNull(_THREE_BYTE_LIMIT));
         dart.assert(dart.notNull(rune) <= dart.notNull(_FOUR_BYTE_LIMIT));
-        this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 240 | dart.notNull(rune) >> 18);
-        this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) >> 12 & 63);
-        this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) >> 6 & 63);
-        this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) & 63);
+        this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 240 | dart.notNull(rune) >> 18);
+        this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) >> 12 & 63);
+        this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) >> 6 & 63);
+        this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) & 63);
         return true;
       } else {
-        this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 224 | dart.notNull(leadingSurrogate) >> 12);
-        this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 128 | dart.notNull(leadingSurrogate) >> 6 & 63);
-        this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 128 | dart.notNull(leadingSurrogate) & 63);
+        this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 224 | dart.notNull(leadingSurrogate) >> 12);
+        this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(leadingSurrogate) >> 6 & 63);
+        this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(leadingSurrogate) & 63);
         return false;
       }
     }
@@ -1731,7 +1731,7 @@ var convert;
         if (dart.notNull(codeUnit) <= dart.notNull(_ONE_BYTE_LIMIT)) {
           if (dart.notNull(this[_bufferIndex]) >= dart.notNull(this[_buffer].length))
             break;
-          this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), codeUnit);
+          this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), codeUnit);
         } else if (_isLeadSurrogate(codeUnit)) {
           if (dart.notNull(this[_bufferIndex]) + 3 >= dart.notNull(this[_buffer].length))
             break;
@@ -1744,15 +1744,15 @@ var convert;
           if (dart.notNull(rune) <= dart.notNull(_TWO_BYTE_LIMIT)) {
             if (dart.notNull(this[_bufferIndex]) + 1 >= dart.notNull(this[_buffer].length))
               break;
-            this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 192 | dart.notNull(rune) >> 6);
-            this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) & 63);
+            this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 192 | dart.notNull(rune) >> 6);
+            this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) & 63);
           } else {
             dart.assert(dart.notNull(rune) <= dart.notNull(_THREE_BYTE_LIMIT));
             if (dart.notNull(this[_bufferIndex]) + 2 >= dart.notNull(this[_buffer].length))
               break;
-            this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 224 | dart.notNull(rune) >> 12);
-            this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) >> 6 & 63);
-            this[_buffer].set((($tmp) => this[_bufferIndex] = dart.notNull($tmp) + 1, $tmp).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) & 63);
+            this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 224 | dart.notNull(rune) >> 12);
+            this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) >> 6 & 63);
+            this[_buffer].set(((x) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) & 63);
           }
         }
       }
@@ -1762,8 +1762,8 @@ var convert;
   dart.defineNamedConstructor(_Utf8Encoder, 'withBufferSize');
   _Utf8Encoder._DEFAULT_BYTE_BUFFER_SIZE = 1024;
   class _Utf8EncoderSink extends dart.mixin(_Utf8Encoder, StringConversionSinkMixin) {
-    _Utf8EncoderSink($_sink) {
-      this[_sink] = $_sink;
+    _Utf8EncoderSink(sink$) {
+      this[_sink] = sink$;
       super._Utf8Encoder();
     }
     close() {
@@ -1811,8 +1811,8 @@ var convert;
     }
   }
   class Utf8Decoder extends Converter$(core.List$(core.int), core.String) {
-    Utf8Decoder(opt$) {
-      let allowMalformed = opt$ && 'allowMalformed' in opt$ ? opt$.allowMalformed : false;
+    Utf8Decoder(opts) {
+      let allowMalformed = opts && 'allowMalformed' in opts ? opts.allowMalformed : false;
       this[_allowMalformed] = allowMalformed;
       super.Converter();
     }
@@ -1877,9 +1877,9 @@ var convert;
   let _expectedUnits = Symbol('_expectedUnits');
   let _extraUnits = Symbol('_extraUnits');
   class _Utf8Decoder extends core.Object {
-    _Utf8Decoder($_stringSink, $_allowMalformed) {
-      this[_stringSink] = $_stringSink;
-      this[_allowMalformed] = $_allowMalformed;
+    _Utf8Decoder(stringSink$, allowMalformed$) {
+      this[_stringSink] = stringSink$;
+      this[_allowMalformed] = allowMalformed$;
       this[_isFirstCharacter] = true;
       this[_value] = 0;
       this[_expectedUnits] = 0;
@@ -1977,7 +1977,7 @@ var convert;
               if (i === endIndex)
                 break;
             }
-            let unit = codeUnits.get((($tmp) => i = dart.notNull($tmp) + 1, $tmp)(i));
+            let unit = codeUnits.get(((x) => i = dart.notNull(x$) + 1, x$)(i));
             if (dart.notNull(unit) < 0) {
               if (!dart.notNull(this[_allowMalformed])) {
                 throw new core.FormatException(`Negative UTF-8 code unit: -0x${(-dart.notNull(unit)).toRadixString(16)}`);
@@ -2071,16 +2071,16 @@ var convert;
   let _process = Symbol('_process');
   let _computeKeys = Symbol('_computeKeys');
   let _upgrade = Symbol('_upgrade');
-  let _hasProperty = Symbol('_hasProperty');
-  let _getProperty = Symbol('_getProperty');
-  let _setProperty = Symbol('_setProperty');
-  let _getPropertyNames = Symbol('_getPropertyNames');
-  let _isUnprocessed = Symbol('_isUnprocessed');
-  let _newJavaScriptObject = Symbol('_newJavaScriptObject');
+  let _hasProperty$ = Symbol('_hasProperty');
+  let _getProperty$ = Symbol('_getProperty');
+  let _setProperty$ = Symbol('_setProperty');
+  let _getPropertyNames$ = Symbol('_getPropertyNames');
+  let _isUnprocessed$ = Symbol('_isUnprocessed');
+  let _newJavaScriptObject$ = Symbol('_newJavaScriptObject');
   class _JsonMap extends core.Object {
-    _JsonMap($_original) {
+    _JsonMap(original$) {
       this[_processed] = _newJavaScriptObject();
-      this[_original] = $_original;
+      this[_original] = original$;
       this[_data] = null;
     }
     get(key) {
@@ -2234,29 +2234,29 @@ var convert;
       let result = _convertJsonToDartLazy(_getProperty(this[_original], key));
       return _setProperty(this[_processed], key, result);
     }
-    static [_hasProperty](object, key) {
+    static [_hasProperty$](object, key) {
       return Object.prototype.hasOwnProperty.call(object, key);
     }
-    static [_getProperty](object, key) {
+    static [_getProperty$](object, key) {
       return object[key];
     }
-    static [_setProperty](object, key, value) {
+    static [_setProperty$](object, key, value) {
       return object[key] = value;
     }
-    static [_getPropertyNames](object) {
+    static [_getPropertyNames$](object) {
       return dart.as(Object.keys(object), core.List);
     }
-    static [_isUnprocessed](object) {
+    static [_isUnprocessed$](object) {
       return typeof object == "undefined";
     }
-    static [_newJavaScriptObject]() {
+    static [_newJavaScriptObject$]() {
       return Object.create(null);
     }
   }
   let _parent = Symbol('_parent');
   class _JsonMapKeyIterable extends _internal.ListIterable {
-    _JsonMapKeyIterable($_parent) {
-      this[_parent] = $_parent;
+    _JsonMapKeyIterable(parent) {
+      this[_parent] = parent;
       super.ListIterable();
     }
     get length() {
@@ -2273,9 +2273,9 @@ var convert;
     }
   }
   class _JsonDecoderSink extends _StringSinkConversionSink {
-    _JsonDecoderSink($_reviver, $_sink) {
-      this[_reviver] = $_reviver;
-      this[_sink] = $_sink;
+    _JsonDecoderSink(reviver$, sink$) {
+      this[_reviver] = reviver$;
+      this[_sink] = sink$;
       super._StringSinkConversionSink(new core.StringBuffer());
     }
     close() {
diff --git a/pkg/dev_compiler/lib/runtime/dart/core.js b/pkg/dev_compiler/lib/runtime/dart/core.js
index 378577226734..d73750389a3d 100644
--- a/pkg/dev_compiler/lib/runtime/dart/core.js
+++ b/pkg/dev_compiler/lib/runtime/dart/core.js
@@ -46,8 +46,8 @@ var core;
   }
   let proxy = new _Proxy();
   class bool extends Object {
-    bool$fromEnvironment(name, opt$) {
-      let defaultValue = opt$ && 'defaultValue' in opt$ ? opt$.defaultValue : false;
+    bool$fromEnvironment(name, opts) {
+      let defaultValue = opts && 'defaultValue' in opts ? opts.defaultValue : false;
       throw new UnsupportedError('bool.fromEnvironment can only be used as a const constructor');
     }
     toString() {
@@ -64,11 +64,11 @@ var core;
     return Comparable;
   });
   let Comparable = Comparable$(dart.dynamic);
-  let _fourDigits = dart.JsSymbol('_fourDigits');
-  let _sixDigits = dart.JsSymbol('_sixDigits');
-  let _threeDigits = dart.JsSymbol('_threeDigits');
-  let _twoDigits = dart.JsSymbol('_twoDigits');
-  let _brokenDownDateToMillisecondsSinceEpoch = dart.JsSymbol('_brokenDownDateToMillisecondsSinceEpoch');
+  let _fourDigits$ = dart.JsSymbol('_fourDigits');
+  let _sixDigits$ = dart.JsSymbol('_sixDigits');
+  let _threeDigits$ = dart.JsSymbol('_threeDigits');
+  let _twoDigits$ = dart.JsSymbol('_twoDigits');
+  let _brokenDownDateToMillisecondsSinceEpoch$ = dart.JsSymbol('_brokenDownDateToMillisecondsSinceEpoch');
   class DateTime extends Object {
     DateTime(year, month, day, hour, minute, second, millisecond) {
       if (month === void 0)
@@ -153,8 +153,8 @@ var core;
         throw new FormatException("Invalid date format", formattedString);
       }
     }
-    DateTime$fromMillisecondsSinceEpoch(millisecondsSinceEpoch, opt$) {
-      let isUtc = opt$ && 'isUtc' in opt$ ? opt$.isUtc : false;
+    DateTime$fromMillisecondsSinceEpoch(millisecondsSinceEpoch, opts) {
+      let isUtc = opts && 'isUtc' in opts ? opts.isUtc : false;
       this.millisecondsSinceEpoch = millisecondsSinceEpoch;
       this.isUtc = isUtc;
       if (dart.notNull(millisecondsSinceEpoch.abs()) > dart.notNull(DateTime._MAX_MILLISECONDS_SINCE_EPOCH)) {
@@ -194,7 +194,7 @@ var core;
         return this;
       return new DateTime.fromMillisecondsSinceEpoch(this.millisecondsSinceEpoch, {isUtc: true});
     }
-    static [_fourDigits](n) {
+    static [_fourDigits$](n) {
       let absN = n.abs();
       let sign = dart.notNull(n) < 0 ? "-" : "";
       if (dart.notNull(absN) >= 1000)
@@ -205,7 +205,7 @@ var core;
         return `${sign}00${absN}`;
       return `${sign}000${absN}`;
     }
-    static [_sixDigits](n) {
+    static [_sixDigits$](n) {
       dart.assert(dart.notNull(n) < -9999 || dart.notNull(n) > 9999);
       let absN = n.abs();
       let sign = dart.notNull(n) < 0 ? "-" : "+";
@@ -213,14 +213,14 @@ var core;
         return `${sign}${absN}`;
       return `${sign}0${absN}`;
     }
-    static [_threeDigits](n) {
+    static [_threeDigits$](n) {
       if (dart.notNull(n) >= 100)
         return `${n}`;
       if (dart.notNull(n) >= 10)
         return `0${n}`;
       return `00${n}`;
     }
-    static [_twoDigits](n) {
+    static [_twoDigits$](n) {
       if (dart.notNull(n) >= 10)
         return `${n}`;
       return `0${n}`;
@@ -274,7 +274,7 @@ var core;
       this.isUtc = false;
       this.millisecondsSinceEpoch = _js_helper.Primitives.dateNow();
     }
-    static [_brokenDownDateToMillisecondsSinceEpoch](year, month, day, hour, minute, second, millisecond, isUtc) {
+    static [_brokenDownDateToMillisecondsSinceEpoch$](year, month, day, hour, minute, second, millisecond, isUtc) {
       return dart.as(_js_helper.Primitives.valueFromDecomposedDate(year, month, day, hour, minute, second, millisecond, isUtc), int);
     }
     get timeZoneName() {
@@ -339,8 +339,8 @@ var core;
   DateTime.DECEMBER = 12;
   DateTime.MONTHS_PER_YEAR = 12;
   DateTime._MAX_MILLISECONDS_SINCE_EPOCH = 8640000000000000;
-  let _onParseErrorInt = dart.JsSymbol('_onParseErrorInt');
-  let _onParseErrorDouble = dart.JsSymbol('_onParseErrorDouble');
+  let _onParseErrorInt$ = dart.JsSymbol('_onParseErrorInt');
+  let _onParseErrorDouble$ = dart.JsSymbol('_onParseErrorDouble');
   class num extends Object {
     static parse(input, onError) {
       if (onError === void 0)
@@ -358,11 +358,11 @@ var core;
         throw new FormatException(input);
       return onError(input);
     }
-    static [_onParseErrorInt](_) {
+    static [_onParseErrorInt$](_) {
       _parseError = true;
       return 0;
     }
-    static [_onParseErrorDouble](_) {
+    static [_onParseErrorDouble$](_) {
       _parseError = true;
       return 0.0;
     }
@@ -382,17 +382,17 @@ var core;
   double.MAX_FINITE = 1.7976931348623157e+308;
   let _duration = dart.JsSymbol('_duration');
   class Duration extends Object {
-    Duration(opt$) {
-      let days = opt$ && 'days' in opt$ ? opt$.days : 0;
-      let hours = opt$ && 'hours' in opt$ ? opt$.hours : 0;
-      let minutes = opt$ && 'minutes' in opt$ ? opt$.minutes : 0;
-      let seconds = opt$ && 'seconds' in opt$ ? opt$.seconds : 0;
-      let milliseconds = opt$ && 'milliseconds' in opt$ ? opt$.milliseconds : 0;
-      let microseconds = opt$ && 'microseconds' in opt$ ? opt$.microseconds : 0;
+    Duration(opts) {
+      let days = opts && 'days' in opts ? opts.days : 0;
+      let hours = opts && 'hours' in opts ? opts.hours : 0;
+      let minutes = opts && 'minutes' in opts ? opts.minutes : 0;
+      let seconds = opts && 'seconds' in opts ? opts.seconds : 0;
+      let milliseconds = opts && 'milliseconds' in opts ? opts.milliseconds : 0;
+      let microseconds = opts && 'microseconds' in opts ? opts.microseconds : 0;
       this.Duration$_microseconds(dart.notNull(days) * dart.notNull(Duration.MICROSECONDS_PER_DAY) + dart.notNull(hours) * dart.notNull(Duration.MICROSECONDS_PER_HOUR) + dart.notNull(minutes) * dart.notNull(Duration.MICROSECONDS_PER_MINUTE) + dart.notNull(seconds) * dart.notNull(Duration.MICROSECONDS_PER_SECOND) + dart.notNull(milliseconds) * dart.notNull(Duration.MICROSECONDS_PER_MILLISECOND) + dart.notNull(microseconds));
     }
-    Duration$_microseconds($_duration) {
-      this[_duration] = $_duration;
+    Duration$_microseconds(duration$) {
+      this[_duration] = duration$;
     }
     ['+'](other) {
       return new Duration._microseconds(dart.notNull(this[_duration]) + dart.notNull(other[_duration]));
@@ -505,8 +505,8 @@ var core;
   Duration.SECONDS_PER_DAY = dart.notNull(Duration.SECONDS_PER_HOUR) * dart.notNull(Duration.HOURS_PER_DAY);
   Duration.MINUTES_PER_DAY = dart.notNull(Duration.MINUTES_PER_HOUR) * dart.notNull(Duration.HOURS_PER_DAY);
   Duration.ZERO = new Duration({seconds: 0});
-  let _stringToSafeString = dart.JsSymbol('_stringToSafeString');
-  let _objectToString = dart.JsSymbol('_objectToString');
+  let _stringToSafeString$ = dart.JsSymbol('_stringToSafeString');
+  let _objectToString$ = dart.JsSymbol('_objectToString');
   class Error extends Object {
     Error() {
     }
@@ -519,10 +519,10 @@ var core;
       }
       return _objectToString(object);
     }
-    static [_stringToSafeString](string) {
+    static [_stringToSafeString$](string) {
       return _js_helper.jsonEncodeNative(string);
     }
-    static [_objectToString](object) {
+    static [_objectToString$](object) {
       return _js_helper.Primitives.objectToString(object);
     }
     get stackTrace() {
@@ -720,8 +720,8 @@ var core;
   }
   let _className = dart.JsSymbol('_className');
   class AbstractClassInstantiationError extends Error {
-    AbstractClassInstantiationError($_className) {
-      this[_className] = $_className;
+    AbstractClassInstantiationError(className) {
+      this[_className] = className;
       super.Error();
     }
     toString() {
@@ -996,7 +996,7 @@ var core;
       [_getKey]() {
         let key = dart.as(_js_helper.Primitives.getProperty(this, Expando._KEY_PROPERTY_NAME), String);
         if (key === null) {
-          key = `expando$key$${(($tmp) => _keyCount = dart.notNull($tmp) + 1, $tmp)(_keyCount)}`;
+          key = `expando$key$${((x) => _keyCount = dart.notNull(x$) + 1, x$)(_keyCount)}`;
           _js_helper.Primitives.setProperty(this, Expando._KEY_PROPERTY_NAME, key);
         }
         return key;
@@ -1008,14 +1008,14 @@ var core;
     return Expando;
   });
   let Expando = Expando$(dart.dynamic);
-  let _toMangledNames = dart.JsSymbol('_toMangledNames');
+  let _toMangledNames$ = dart.JsSymbol('_toMangledNames');
   class Function extends Object {
     static apply(f, positionalArguments, namedArguments) {
       if (namedArguments === void 0)
         namedArguments = null;
       return _js_helper.Primitives.applyFunction(f, positionalArguments, namedArguments === null ? null : _toMangledNames(namedArguments));
     }
-    static [_toMangledNames](namedArguments) {
+    static [_toMangledNames$](namedArguments) {
       let result = dart.as(dart.map(), Map$(String, dynamic));
       namedArguments.forEach(dart.closureWrap((symbol, value) => {
         result.set(_symbolToString(dart.as(symbol, Symbol)), value);
@@ -1032,13 +1032,13 @@ var core;
     return _js_helper.objectHashCode(object);
   }
   class int extends num {
-    int$fromEnvironment(name, opt$) {
-      let defaultValue = opt$ && 'defaultValue' in opt$ ? opt$.defaultValue : null;
+    int$fromEnvironment(name, opts) {
+      let defaultValue = opts && 'defaultValue' in opts ? opts.defaultValue : null;
       throw new UnsupportedError('int.fromEnvironment can only be used as a const constructor');
     }
-    static parse(source, opt$) {
-      let radix = opt$ && 'radix' in opt$ ? opt$.radix : null;
-      let onError = opt$ && 'onError' in opt$ ? opt$.onError : null;
+    static parse(source, opts) {
+      let radix = opts && 'radix' in opts ? opts.radix : null;
+      let onError = opts && 'onError' in opts ? opts.onError : null;
       return Number(source);
     }
   }
@@ -1083,19 +1083,19 @@ var core;
   let _end = dart.JsSymbol('_end');
   let _start = dart.JsSymbol('_start');
   let _generator = dart.JsSymbol('_generator');
-  let _id = dart.JsSymbol('_id');
+  let _id$ = dart.JsSymbol('_id');
   let _GeneratorIterable$ = dart.generic(function(E) {
     class _GeneratorIterable extends collection.IterableBase$(E) {
-      _GeneratorIterable($_end, generator) {
-        this[_end] = $_end;
+      _GeneratorIterable(end$, generator) {
+        this[_end] = end$;
         this[_start] = 0;
         this[_generator] = dart.as(generator !== null ? generator : _id, _Generator);
         super.IterableBase();
       }
-      _GeneratorIterable$slice($_start, $_end, $_generator) {
-        this[_start] = $_start;
-        this[_end] = $_end;
-        this[_generator] = $_generator;
+      _GeneratorIterable$slice(start$, end$, generator$) {
+        this[_start] = start$;
+        this[_end] = end$;
+        this[_generator] = generator$;
         super.IterableBase();
       }
       get iterator() {
@@ -1122,7 +1122,7 @@ var core;
           return this;
         return new _GeneratorIterable.slice(this[_start], newEnd, this[_generator]);
       }
-      static [_id](n) {
+      static [_id$](n) {
         return n;
       }
     }
@@ -1134,10 +1134,10 @@ var core;
   let _current = dart.JsSymbol('_current');
   let _GeneratorIterator$ = dart.generic(function(E) {
     class _GeneratorIterator extends Object {
-      _GeneratorIterator($_index, $_end, $_generator) {
-        this[_index] = $_index;
-        this[_end] = $_end;
-        this[_generator] = $_generator;
+      _GeneratorIterator(index$, end$, generator$) {
+        this[_index] = index$;
+        this[_end] = end$;
+        this[_generator] = generator$;
         this[_current] = null;
       }
       moveNext() {
@@ -1188,17 +1188,17 @@ var core;
         }
         return dart.as(result, List$(E));
       }
-      List$from(elements, opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      List$from(elements, opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         return null;
       }
-      List$generate(length, generator, opt$) {
-        let growable = opt$ && 'growable' in opt$ ? opt$.growable : true;
+      List$generate(length, generator, opts) {
+        let growable = opts && 'growable' in opts ? opts.growable : true;
         let result = null;
         if (growable) {
-          result = ((_) => {
-            _.length = length;
-            return _;
+          result = ((_$) => {
+            _$.length = length;
+            return _$;
           }).bind(this)(new List.from([]));
         } else {
           result = new List(length);
@@ -1226,8 +1226,8 @@ var core;
       Map$identity() {
         return new collection.LinkedHashMap.identity();
       }
-      Map$fromIterable(iterable, opt$) {
-        return new collection.LinkedHashMap.fromIterable(iterable, opt$);
+      Map$fromIterable(iterable, opts) {
+        return new collection.LinkedHashMap.fromIterable(iterable, opts);
       }
       Map$fromIterables(keys, values) {
         return new collection.LinkedHashMap.fromIterables(keys, values);
@@ -1263,9 +1263,9 @@ var core;
   class Match extends Object {
   }
   class RegExp extends Object {
-    RegExp(source, opt$) {
-      let multiLine = opt$ && 'multiLine' in opt$ ? opt$.multiLine : false;
-      let caseSensitive = opt$ && 'caseSensitive' in opt$ ? opt$.caseSensitive : true;
+    RegExp(source, opts) {
+      let multiLine = opts && 'multiLine' in opts ? opts.multiLine : false;
+      let caseSensitive = opts && 'caseSensitive' in opts ? opts.caseSensitive : true;
       return new _js_helper.JSSyntaxRegExp(source, {multiLine: multiLine, caseSensitive: caseSensitive});
     }
   }
@@ -1295,8 +1295,8 @@ var core;
   class StackTrace extends Object {
   }
   let _stop = dart.JsSymbol('_stop');
-  let _initTicker = dart.JsSymbol('_initTicker');
-  let _now = dart.JsSymbol('_now');
+  let _initTicker$ = dart.JsSymbol('_initTicker');
+  let _now$ = dart.JsSymbol('_now');
   class Stopwatch extends Object {
     get frequency() {
       return _frequency;
@@ -1347,16 +1347,16 @@ var core;
     get isRunning() {
       return this[_start] !== null && this[_stop] === null;
     }
-    static [_initTicker]() {
+    static [_initTicker$]() {
       _js_helper.Primitives.initTicker();
       _frequency = _js_helper.Primitives.timerFrequency;
     }
-    static [_now]() {
+    static [_now$]() {
       return dart.as(dart.dinvoke(_js_helper.Primitives, 'timerTicks'), int);
     }
   }
   Stopwatch._frequency = null;
-  let _stringFromIterable = dart.JsSymbol('_stringFromIterable');
+  let _stringFromIterable$ = dart.JsSymbol('_stringFromIterable');
   class String extends Object {
     String$fromCharCodes(charCodes, start, end) {
       if (start === void 0)
@@ -1384,11 +1384,11 @@ var core;
     String$fromCharCode(charCode) {
       return _js_helper.Primitives.stringFromCharCode(charCode);
     }
-    String$fromEnvironment(name, opt$) {
-      let defaultValue = opt$ && 'defaultValue' in opt$ ? opt$.defaultValue : null;
+    String$fromEnvironment(name, opts) {
+      let defaultValue = opts && 'defaultValue' in opts ? opts.defaultValue : null;
       throw new UnsupportedError('String.fromEnvironment can only be used as a const constructor');
     }
-    static [_stringFromIterable](charCodes, start, end) {
+    static [_stringFromIterable$](charCodes, start, end) {
       if (dart.notNull(start) < 0)
         throw new RangeError.range(start, 0, charCodes.length);
       if (end !== null && dart.notNull(end) < dart.notNull(start)) {
@@ -1623,49 +1623,49 @@ var core;
   let _userInfo = dart.JsSymbol('_userInfo');
   let _host = dart.JsSymbol('_host');
   let _port = dart.JsSymbol('_port');
-  let _defaultPort = dart.JsSymbol('_defaultPort');
+  let _defaultPort$ = dart.JsSymbol('_defaultPort');
   let _path = dart.JsSymbol('_path');
   let _query = dart.JsSymbol('_query');
   let _fragment = dart.JsSymbol('_fragment');
-  let _fail = dart.JsSymbol('_fail');
+  let _fail$ = dart.JsSymbol('_fail');
   let _pathSegments = dart.JsSymbol('_pathSegments');
   let _queryParameters = dart.JsSymbol('_queryParameters');
-  let _makeHttpUri = dart.JsSymbol('_makeHttpUri');
-  let _isWindows = dart.JsSymbol('_isWindows');
-  let _checkNonWindowsPathReservedCharacters = dart.JsSymbol('_checkNonWindowsPathReservedCharacters');
-  let _checkWindowsPathReservedCharacters = dart.JsSymbol('_checkWindowsPathReservedCharacters');
-  let _checkWindowsDriveLetter = dart.JsSymbol('_checkWindowsDriveLetter');
-  let _makeFileUri = dart.JsSymbol('_makeFileUri');
-  let _makeWindowsFileUrl = dart.JsSymbol('_makeWindowsFileUrl');
-  let _makePort = dart.JsSymbol('_makePort');
-  let _makeHost = dart.JsSymbol('_makeHost');
-  let _isRegNameChar = dart.JsSymbol('_isRegNameChar');
-  let _normalizeRegName = dart.JsSymbol('_normalizeRegName');
-  let _makeScheme = dart.JsSymbol('_makeScheme');
-  let _makeUserInfo = dart.JsSymbol('_makeUserInfo');
-  let _makePath = dart.JsSymbol('_makePath');
-  let _makeQuery = dart.JsSymbol('_makeQuery');
-  let _makeFragment = dart.JsSymbol('_makeFragment');
-  let _stringOrNullLength = dart.JsSymbol('_stringOrNullLength');
-  let _isHexDigit = dart.JsSymbol('_isHexDigit');
-  let _hexValue = dart.JsSymbol('_hexValue');
-  let _normalizeEscape = dart.JsSymbol('_normalizeEscape');
-  let _isUnreservedChar = dart.JsSymbol('_isUnreservedChar');
-  let _escapeChar = dart.JsSymbol('_escapeChar');
-  let _normalize = dart.JsSymbol('_normalize');
-  let _isSchemeCharacter = dart.JsSymbol('_isSchemeCharacter');
-  let _isGeneralDelimiter = dart.JsSymbol('_isGeneralDelimiter');
+  let _makeHttpUri$ = dart.JsSymbol('_makeHttpUri');
+  let _isWindows$ = dart.JsSymbol('_isWindows');
+  let _checkNonWindowsPathReservedCharacters$ = dart.JsSymbol('_checkNonWindowsPathReservedCharacters');
+  let _checkWindowsPathReservedCharacters$ = dart.JsSymbol('_checkWindowsPathReservedCharacters');
+  let _checkWindowsDriveLetter$ = dart.JsSymbol('_checkWindowsDriveLetter');
+  let _makeFileUri$ = dart.JsSymbol('_makeFileUri');
+  let _makeWindowsFileUrl$ = dart.JsSymbol('_makeWindowsFileUrl');
+  let _makePort$ = dart.JsSymbol('_makePort');
+  let _makeHost$ = dart.JsSymbol('_makeHost');
+  let _isRegNameChar$ = dart.JsSymbol('_isRegNameChar');
+  let _normalizeRegName$ = dart.JsSymbol('_normalizeRegName');
+  let _makeScheme$ = dart.JsSymbol('_makeScheme');
+  let _makeUserInfo$ = dart.JsSymbol('_makeUserInfo');
+  let _makePath$ = dart.JsSymbol('_makePath');
+  let _makeQuery$ = dart.JsSymbol('_makeQuery');
+  let _makeFragment$ = dart.JsSymbol('_makeFragment');
+  let _stringOrNullLength$ = dart.JsSymbol('_stringOrNullLength');
+  let _isHexDigit$ = dart.JsSymbol('_isHexDigit');
+  let _hexValue$ = dart.JsSymbol('_hexValue');
+  let _normalizeEscape$ = dart.JsSymbol('_normalizeEscape');
+  let _isUnreservedChar$ = dart.JsSymbol('_isUnreservedChar');
+  let _escapeChar$ = dart.JsSymbol('_escapeChar');
+  let _normalize$ = dart.JsSymbol('_normalize');
+  let _isSchemeCharacter$ = dart.JsSymbol('_isSchemeCharacter');
+  let _isGeneralDelimiter$ = dart.JsSymbol('_isGeneralDelimiter');
   let _merge = dart.JsSymbol('_merge');
   let _hasDotSegments = dart.JsSymbol('_hasDotSegments');
   let _removeDotSegments = dart.JsSymbol('_removeDotSegments');
   let _toWindowsFilePath = dart.JsSymbol('_toWindowsFilePath');
   let _toFilePath = dart.JsSymbol('_toFilePath');
   let _isPathAbsolute = dart.JsSymbol('_isPathAbsolute');
-  let _addIfNonEmpty = dart.JsSymbol('_addIfNonEmpty');
-  let _uriEncode = dart.JsSymbol('_uriEncode');
-  let _hexCharPairToByte = dart.JsSymbol('_hexCharPairToByte');
-  let _uriDecode = dart.JsSymbol('_uriDecode');
-  let _isAlphabeticCharacter = dart.JsSymbol('_isAlphabeticCharacter');
+  let _addIfNonEmpty$ = dart.JsSymbol('_addIfNonEmpty');
+  let _uriEncode$ = dart.JsSymbol('_uriEncode');
+  let _hexCharPairToByte$ = dart.JsSymbol('_hexCharPairToByte');
+  let _uriDecode$ = dart.JsSymbol('_uriDecode');
+  let _isAlphabeticCharacter$ = dart.JsSymbol('_isAlphabeticCharacter');
   class Uri extends Object {
     get authority() {
       if (!dart.notNull(this.hasAuthority))
@@ -1690,7 +1690,7 @@ var core;
         return _defaultPort(this.scheme);
       return this[_port];
     }
-    static [_defaultPort](scheme) {
+    static [_defaultPort$](scheme) {
       if (dart.equals(scheme, "http"))
         return 80;
       if (dart.equals(scheme, "https"))
@@ -1870,30 +1870,30 @@ var core;
       }
       return new Uri._internal(scheme, userinfo, host, port, path, query, fragment);
     }
-    static [_fail](uri, index, message) {
+    static [_fail$](uri, index, message) {
       throw new FormatException(message, uri, index);
     }
-    Uri$_internal(scheme, $_userInfo, $_host, $_port, $_path, $_query, $_fragment) {
+    Uri$_internal(scheme, userInfo$, host$, port$, path$, query$, fragment$) {
       this.scheme = scheme;
-      this[_userInfo] = $_userInfo;
-      this[_host] = $_host;
-      this[_port] = $_port;
-      this[_path] = $_path;
-      this[_query] = $_query;
-      this[_fragment] = $_fragment;
+      this[_userInfo] = userInfo$;
+      this[_host] = host$;
+      this[_port] = port$;
+      this[_path] = path$;
+      this[_query] = query$;
+      this[_fragment] = fragment$;
       this[_pathSegments] = null;
       this[_queryParameters] = null;
     }
-    Uri(opt$) {
-      let scheme = opt$ && 'scheme' in opt$ ? opt$.scheme : "";
-      let userInfo = opt$ && 'userInfo' in opt$ ? opt$.userInfo : "";
-      let host = opt$ && 'host' in opt$ ? opt$.host : null;
-      let port = opt$ && 'port' in opt$ ? opt$.port : null;
-      let path = opt$ && 'path' in opt$ ? opt$.path : null;
-      let pathSegments = opt$ && 'pathSegments' in opt$ ? opt$.pathSegments : null;
-      let query = opt$ && 'query' in opt$ ? opt$.query : null;
-      let queryParameters = opt$ && 'queryParameters' in opt$ ? opt$.queryParameters : null;
-      let fragment = opt$ && 'fragment' in opt$ ? opt$.fragment : null;
+    Uri(opts) {
+      let scheme = opts && 'scheme' in opts ? opts.scheme : "";
+      let userInfo = opts && 'userInfo' in opts ? opts.userInfo : "";
+      let host = opts && 'host' in opts ? opts.host : null;
+      let port = opts && 'port' in opts ? opts.port : null;
+      let path = opts && 'path' in opts ? opts.path : null;
+      let pathSegments = opts && 'pathSegments' in opts ? opts.pathSegments : null;
+      let query = opts && 'query' in opts ? opts.query : null;
+      let queryParameters = opts && 'queryParameters' in opts ? opts.queryParameters : null;
+      let fragment = opts && 'fragment' in opts ? opts.fragment : null;
       scheme = _makeScheme(scheme, _stringOrNullLength(scheme));
       userInfo = _makeUserInfo(userInfo, 0, _stringOrNullLength(userInfo));
       host = _makeHost(host, 0, _stringOrNullLength(host), false);
@@ -1920,7 +1920,7 @@ var core;
         queryParameters = null;
       return _makeHttpUri("https", authority, unencodedPath, queryParameters);
     }
-    static [_makeHttpUri](scheme, authority, unencodedPath, queryParameters) {
+    static [_makeHttpUri$](scheme, authority, unencodedPath, queryParameters) {
       let userInfo = "";
       let host = null;
       let port = null;
@@ -1963,9 +1963,9 @@ var core;
       }
       return new Uri({scheme: scheme, userInfo: userInfo, host: dart.as(host, String), port: dart.as(port, int), pathSegments: unencodedPath.split("/"), queryParameters: queryParameters});
     }
-    Uri$file(path, opt$) {
-      let windows = opt$ && 'windows' in opt$ ? opt$.windows : null;
-      windows = windows === null ? Uri[_isWindows] : windows;
+    Uri$file(path, opts) {
+      let windows = opts && 'windows' in opts ? opts.windows : null;
+      windows = windows === null ? Uri[_isWindows$] : windows;
       return dart.as(windows ? _makeWindowsFileUrl(path) : _makeFileUri(path), Uri);
     }
     static get base() {
@@ -1974,10 +1974,10 @@ var core;
         return Uri.parse(uri);
       throw new UnsupportedError("'Uri.base' is not supported");
     }
-    static get [_isWindows]() {
+    static get [_isWindows$]() {
       return false;
     }
-    static [_checkNonWindowsPathReservedCharacters](segments, argumentError) {
+    static [_checkNonWindowsPathReservedCharacters$](segments, argumentError) {
       segments.forEach(dart.closureWrap((segment) => {
         if (dart.dinvoke(segment, 'contains', "/")) {
           if (argumentError) {
@@ -1988,7 +1988,7 @@ var core;
         }
       }, "(String) → void"));
     }
-    static [_checkWindowsPathReservedCharacters](segments, argumentError, firstSegment) {
+    static [_checkWindowsPathReservedCharacters$](segments, argumentError, firstSegment) {
       if (firstSegment === void 0)
         firstSegment = 0;
       segments.skip(firstSegment).forEach(dart.closureWrap((segment) => {
@@ -2001,7 +2001,7 @@ var core;
         }
       }, "(String) → void"));
     }
-    static [_checkWindowsDriveLetter](charCode, argumentError) {
+    static [_checkWindowsDriveLetter$](charCode, argumentError) {
       if (dart.notNull(Uri._UPPER_CASE_A) <= dart.notNull(charCode) && dart.notNull(charCode) <= dart.notNull(Uri._UPPER_CASE_Z) || dart.notNull(Uri._LOWER_CASE_A) <= dart.notNull(charCode) && dart.notNull(charCode) <= dart.notNull(Uri._LOWER_CASE_Z)) {
         return;
       }
@@ -2011,7 +2011,7 @@ var core;
         throw new UnsupportedError(String['+']("Illegal drive letter ", new String.fromCharCode(charCode)));
       }
     }
-    static [_makeFileUri](path) {
+    static [_makeFileUri$](path) {
       let sep = "/";
       if (path.startsWith(sep)) {
         return new Uri({scheme: "file", pathSegments: path.split(sep)});
@@ -2019,7 +2019,7 @@ var core;
         return new Uri({pathSegments: path.split(sep)});
       }
     }
-    static [_makeWindowsFileUrl](path) {
+    static [_makeWindowsFileUrl$](path) {
       if (path.startsWith("\\\\?\\")) {
         if (path.startsWith("\\\\?\\UNC\\")) {
           path = `\\${path.substring(7)}`;
@@ -2061,16 +2061,16 @@ var core;
         return new Uri({pathSegments: pathSegments});
       }
     }
-    replace(opt$) {
-      let scheme = opt$ && 'scheme' in opt$ ? opt$.scheme : null;
-      let userInfo = opt$ && 'userInfo' in opt$ ? opt$.userInfo : null;
-      let host = opt$ && 'host' in opt$ ? opt$.host : null;
-      let port = opt$ && 'port' in opt$ ? opt$.port : null;
-      let path = opt$ && 'path' in opt$ ? opt$.path : null;
-      let pathSegments = opt$ && 'pathSegments' in opt$ ? opt$.pathSegments : null;
-      let query = opt$ && 'query' in opt$ ? opt$.query : null;
-      let queryParameters = opt$ && 'queryParameters' in opt$ ? opt$.queryParameters : null;
-      let fragment = opt$ && 'fragment' in opt$ ? opt$.fragment : null;
+    replace(opts) {
+      let scheme = opts && 'scheme' in opts ? opts.scheme : null;
+      let userInfo = opts && 'userInfo' in opts ? opts.userInfo : null;
+      let host = opts && 'host' in opts ? opts.host : null;
+      let port = opts && 'port' in opts ? opts.port : null;
+      let path = opts && 'path' in opts ? opts.path : null;
+      let pathSegments = opts && 'pathSegments' in opts ? opts.pathSegments : null;
+      let query = opts && 'query' in opts ? opts.query : null;
+      let queryParameters = opts && 'queryParameters' in opts ? opts.queryParameters : null;
+      let fragment = opts && 'fragment' in opts ? opts.fragment : null;
       let schemeChanged = false;
       if (scheme !== null) {
         scheme = _makeScheme(scheme, scheme.length);
@@ -2133,12 +2133,12 @@ var core;
       }
       return this[_queryParameters];
     }
-    static [_makePort](port, scheme) {
+    static [_makePort$](port, scheme) {
       if (port !== null && port === _defaultPort(scheme))
         return null;
       return port;
     }
-    static [_makeHost](host, start, end, strictIPv6) {
+    static [_makeHost$](host, start, end, strictIPv6) {
       if (host === null)
         return null;
       if (start === end)
@@ -2160,10 +2160,10 @@ var core;
       }
       return _normalizeRegName(host, start, end);
     }
-    static [_isRegNameChar](char) {
+    static [_isRegNameChar$](char) {
       return dart.notNull(char) < 127 && dart.notNull(!dart.equals(dart.dbinary(Uri._regNameTable.get(dart.notNull(char) >> 4), '&', 1 << (dart.notNull(char) & 15)), 0));
     }
-    static [_normalizeRegName](host, start, end) {
+    static [_normalizeRegName$](host, start, end) {
       let buffer = null;
       let sectionStart = start;
       let index = start;
@@ -2236,7 +2236,7 @@ var core;
       }
       return buffer.toString();
     }
-    static [_makeScheme](scheme, end) {
+    static [_makeScheme$](scheme, end) {
       if (end === 0)
         return "";
       let firstCodeUnit = scheme.codeUnitAt(0);
@@ -2258,12 +2258,12 @@ var core;
         scheme = scheme.toLowerCase();
       return scheme;
     }
-    static [_makeUserInfo](userInfo, start, end) {
+    static [_makeUserInfo$](userInfo, start, end) {
       if (userInfo === null)
         return "";
       return _normalize(userInfo, start, end, dart.as(Uri._userinfoTable, List$(int)));
     }
-    static [_makePath](path, start, end, pathSegments, ensureLeadingSlash, isFile) {
+    static [_makePath$](path, start, end, pathSegments, ensureLeadingSlash, isFile) {
       if (dart.notNull(path === null) && dart.notNull(pathSegments === null))
         return isFile ? "/" : "";
       if (dart.notNull(path !== null) && dart.notNull(pathSegments !== null)) {
@@ -2283,7 +2283,7 @@ var core;
       }
       return dart.as(result, String);
     }
-    static [_makeQuery](query, start, end, queryParameters) {
+    static [_makeQuery$](query, start, end, queryParameters) {
       if (dart.notNull(query === null) && dart.notNull(queryParameters === null))
         return null;
       if (dart.notNull(query !== null) && dart.notNull(queryParameters !== null)) {
@@ -2306,28 +2306,28 @@ var core;
       }).bind(this), "(String, String) → void"));
       return result.toString();
     }
-    static [_makeFragment](fragment, start, end) {
+    static [_makeFragment$](fragment, start, end) {
       if (fragment === null)
         return null;
       return _normalize(fragment, start, end, dart.as(Uri._queryCharTable, List$(int)));
     }
-    static [_stringOrNullLength](s) {
+    static [_stringOrNullLength$](s) {
       return s === null ? 0 : s.length;
     }
-    static [_isHexDigit](char) {
+    static [_isHexDigit$](char) {
       if (dart.notNull(Uri._NINE) >= dart.notNull(char))
         return dart.notNull(Uri._ZERO) <= dart.notNull(char);
       char = 32;
       return dart.notNull(Uri._LOWER_CASE_A) <= dart.notNull(char) && dart.notNull(Uri._LOWER_CASE_F) >= dart.notNull(char);
     }
-    static [_hexValue](char) {
+    static [_hexValue$](char) {
       dart.assert(_isHexDigit(char));
       if (dart.notNull(Uri._NINE) >= dart.notNull(char))
         return dart.notNull(char) - dart.notNull(Uri._ZERO);
       char = 32;
       return dart.notNull(char) - (dart.notNull(Uri._LOWER_CASE_A) - 10);
     }
-    static [_normalizeEscape](source, index, lowerCase) {
+    static [_normalizeEscape$](source, index, lowerCase) {
       dart.assert(source.codeUnitAt(index) === Uri._PERCENT);
       if (dart.notNull(index) + 2 >= dart.notNull(source.length)) {
         return "%";
@@ -2349,10 +2349,10 @@ var core;
       }
       return null;
     }
-    static [_isUnreservedChar](ch) {
+    static [_isUnreservedChar$](ch) {
       return dart.notNull(ch) < 127 && dart.notNull(!dart.equals(dart.dbinary(Uri._unreservedTable.get(dart.notNull(ch) >> 4), '&', 1 << (dart.notNull(ch) & 15)), 0));
     }
-    static [_escapeChar](char) {
+    static [_escapeChar$](char) {
       dart.assert(dart.dbinary(char, '<=', 1114111));
       let hexDigits = "0123456789ABCDEF";
       let codeUnits = null;
@@ -2385,7 +2385,7 @@ var core;
       }
       return new String.fromCharCodes(dart.as(codeUnits, Iterable$(int)));
     }
-    static [_normalize](component, start, end, charTable) {
+    static [_normalize$](component, start, end, charTable) {
       let buffer = null;
       let sectionStart = start;
       let index = start;
@@ -2439,10 +2439,10 @@ var core;
       }
       return buffer.toString();
     }
-    static [_isSchemeCharacter](ch) {
+    static [_isSchemeCharacter$](ch) {
       return dart.notNull(ch) < 128 && dart.notNull(!dart.equals(dart.dbinary(Uri._schemeTable.get(dart.notNull(ch) >> 4), '&', 1 << (dart.notNull(ch) & 15)), 0));
     }
-    static [_isGeneralDelimiter](ch) {
+    static [_isGeneralDelimiter$](ch) {
       return dart.notNull(ch) <= dart.notNull(Uri._RIGHT_BRACKET) && dart.notNull(!dart.equals(dart.dbinary(Uri._genDelimitersTable.get(dart.notNull(ch) >> 4), '&', 1 << (dart.notNull(ch) & 15)), 0));
     }
     get isAbsolute() {
@@ -2577,8 +2577,8 @@ var core;
         return `${this.scheme}://${this[_host]}`;
       return `${this.scheme}://${this[_host]}:${this[_port]}`;
     }
-    toFilePath(opt$) {
-      let windows = opt$ && 'windows' in opt$ ? opt$.windows : null;
+    toFilePath(opts) {
+      let windows = opts && 'windows' in opts ? opts.windows : null;
       if (dart.notNull(!dart.equals(this.scheme, "")) && dart.notNull(!dart.equals(this.scheme, "file"))) {
         throw new UnsupportedError(`Cannot extract a file path from a ${this.scheme} URI`);
       }
@@ -2674,7 +2674,7 @@ var core;
       }
       return combine(this.scheme, combine(this.userInfo, combine(this.host, combine(this.port, combine(this.path, combine(this.query, combine(this.fragment, 1)))))));
     }
-    static [_addIfNonEmpty](sb, test, first, second) {
+    static [_addIfNonEmpty$](sb, test, first, second) {
       if (!dart.equals("", test)) {
         sb.write(first);
         sb.write(second);
@@ -2683,15 +2683,15 @@ var core;
     static encodeComponent(component) {
       return _uriEncode(dart.as(Uri._unreserved2396Table, List$(int)), component);
     }
-    static encodeQueryComponent(component, opt$) {
-      let encoding = opt$ && 'encoding' in opt$ ? opt$.encoding : convert.UTF8;
+    static encodeQueryComponent(component, opts) {
+      let encoding = opts && 'encoding' in opts ? opts.encoding : convert.UTF8;
       return _uriEncode(dart.as(Uri._unreservedTable, List$(int)), component, {encoding: encoding, spaceToPlus: true});
     }
     static decodeComponent(encodedComponent) {
       return _uriDecode(encodedComponent);
     }
-    static decodeQueryComponent(encodedComponent, opt$) {
-      let encoding = opt$ && 'encoding' in opt$ ? opt$.encoding : convert.UTF8;
+    static decodeQueryComponent(encodedComponent, opts) {
+      let encoding = opts && 'encoding' in opts ? opts.encoding : convert.UTF8;
       return _uriDecode(encodedComponent, {plusToSpace: true, encoding: encoding});
     }
     static encodeFull(uri) {
@@ -2700,8 +2700,8 @@ var core;
     static decodeFull(uri) {
       return _uriDecode(uri);
     }
-    static splitQueryString(query, opt$) {
-      let encoding = opt$ && 'encoding' in opt$ ? opt$.encoding : convert.UTF8;
+    static splitQueryString(query, opts) {
+      let encoding = opts && 'encoding' in opts ? opts.encoding : convert.UTF8;
       return dart.as(query.split("&").fold(dart.map(), dart.closureWrap((map, element) => {
         let index = dart.as(dart.dinvoke(element, 'indexOf', "="), int);
         if (index === -1) {
@@ -2830,9 +2830,9 @@ var core;
       }
       return dart.as(bytes, List$(int));
     }
-    static [_uriEncode](canonicalTable, text, opt$) {
-      let encoding = opt$ && 'encoding' in opt$ ? opt$.encoding : convert.UTF8;
-      let spaceToPlus = opt$ && 'spaceToPlus' in opt$ ? opt$.spaceToPlus : false;
+    static [_uriEncode$](canonicalTable, text, opts) {
+      let encoding = opts && 'encoding' in opts ? opts.encoding : convert.UTF8;
+      let spaceToPlus = opts && 'spaceToPlus' in opts ? opts.spaceToPlus : false;
       // Function byteToHex: (dynamic, dynamic) → dynamic
       function byteToHex(byte, buffer) {
         let hex = '0123456789ABCDEF';
@@ -2854,7 +2854,7 @@ var core;
       }
       return result.toString();
     }
-    static [_hexCharPairToByte](s, pos) {
+    static [_hexCharPairToByte$](s, pos) {
       let byte = 0;
       for (let i = 0; dart.notNull(i) < 2; i = dart.notNull(i) + 1) {
         let charCode = s.codeUnitAt(dart.notNull(pos) + dart.notNull(i));
@@ -2871,9 +2871,9 @@ var core;
       }
       return byte;
     }
-    static [_uriDecode](text, opt$) {
-      let plusToSpace = opt$ && 'plusToSpace' in opt$ ? opt$.plusToSpace : false;
-      let encoding = opt$ && 'encoding' in opt$ ? opt$.encoding : convert.UTF8;
+    static [_uriDecode$](text, opts) {
+      let plusToSpace = opts && 'plusToSpace' in opts ? opts.plusToSpace : false;
+      let encoding = opts && 'encoding' in opts ? opts.encoding : convert.UTF8;
       let simple = true;
       for (let i = 0; dart.notNull(i) < dart.notNull(text.length) && dart.notNull(simple); i = dart.notNull(i) + 1) {
         let codeUnit = text.codeUnitAt(i);
@@ -2908,7 +2908,7 @@ var core;
       }
       return encoding.decode(bytes);
     }
-    static [_isAlphabeticCharacter](codeUnit) {
+    static [_isAlphabeticCharacter$](codeUnit) {
       return dart.notNull(codeUnit) >= dart.notNull(Uri._LOWER_CASE_A) && dart.notNull(codeUnit) <= dart.notNull(Uri._LOWER_CASE_Z) || dart.notNull(codeUnit) >= dart.notNull(Uri._UPPER_CASE_A) && dart.notNull(codeUnit) <= dart.notNull(Uri._UPPER_CASE_Z);
     }
   }
diff --git a/pkg/dev_compiler/lib/runtime/dart/isolate.js b/pkg/dev_compiler/lib/runtime/dart/isolate.js
index e35d63fa3e9a..c265704d4b3b 100644
--- a/pkg/dev_compiler/lib/runtime/dart/isolate.js
+++ b/pkg/dev_compiler/lib/runtime/dart/isolate.js
@@ -16,9 +16,9 @@ var isolate;
   }
   let _pause = Symbol('_pause');
   class Isolate extends core.Object {
-    Isolate(controlPort, opt$) {
-      let pauseCapability = opt$ && 'pauseCapability' in opt$ ? opt$.pauseCapability : null;
-      let terminateCapability = opt$ && 'terminateCapability' in opt$ ? opt$.terminateCapability : null;
+    Isolate(controlPort, opts) {
+      let pauseCapability = opts && 'pauseCapability' in opts ? opts.pauseCapability : null;
+      let terminateCapability = opts && 'terminateCapability' in opts ? opts.terminateCapability : null;
       this.controlPort = controlPort;
       this.pauseCapability = pauseCapability;
       this.terminateCapability = terminateCapability;
@@ -26,8 +26,8 @@ var isolate;
     static get current() {
       return _currentIsolateCache;
     }
-    static spawn(entryPoint, message, opt$) {
-      let paused = opt$ && 'paused' in opt$ ? opt$.paused : false;
+    static spawn(entryPoint, message, opts) {
+      let paused = opts && 'paused' in opts ? opts.paused : false;
       try {
         return dart.as(_isolate_helper.IsolateNatives.spawnFunction(entryPoint, message, paused).then(dart.closureWrap((msg) => new Isolate(dart.as(dart.dindex(msg, 1), SendPort), {pauseCapability: dart.as(dart.dindex(msg, 2), Capability), terminateCapability: dart.as(dart.dindex(msg, 3), Capability)}), "(List<dynamic>) → dynamic")), async.Future$(Isolate));
       } catch (e) {
@@ -36,9 +36,9 @@ var isolate;
       }
 
     }
-    static spawnUri(uri, args, message, opt$) {
-      let paused = opt$ && 'paused' in opt$ ? opt$.paused : false;
-      let packageRoot = opt$ && 'packageRoot' in opt$ ? opt$.packageRoot : null;
+    static spawnUri(uri, args, message, opts) {
+      let paused = opts && 'paused' in opts ? opts.paused : false;
+      let packageRoot = opts && 'packageRoot' in opts ? opts.packageRoot : null;
       if (packageRoot !== null)
         throw new core.UnimplementedError("packageRoot");
       try {
@@ -193,8 +193,8 @@ var isolate;
   }
   let _trace = Symbol('_trace');
   class _RemoteStackTrace extends core.Object {
-    _RemoteStackTrace($_trace) {
-      this[_trace] = $_trace;
+    _RemoteStackTrace(trace) {
+      this[_trace] = trace;
     }
     toString() {
       return this[_trace];
diff --git a/pkg/dev_compiler/lib/runtime/dart/typed_data.js b/pkg/dev_compiler/lib/runtime/dart/typed_data.js
index 5143b2ec21fd..e724ce86d0ef 100644
--- a/pkg/dev_compiler/lib/runtime/dart/typed_data.js
+++ b/pkg/dev_compiler/lib/runtime/dart/typed_data.js
@@ -7,8 +7,8 @@ var typed_data;
   }
   let _littleEndian = Symbol('_littleEndian');
   class Endianness extends core.Object {
-    Endianness$_($_littleEndian) {
-      this[_littleEndian] = $_littleEndian;
+    Endianness$_(littleEndian) {
+      this[_littleEndian] = littleEndian;
     }
   }
   dart.defineNamedConstructor(Endianness, '_');
diff --git a/pkg/dev_compiler/lib/src/codegen/js_codegen.dart b/pkg/dev_compiler/lib/src/codegen/js_codegen.dart
index 0e589ab808dc..3cba7a75f96f 100644
--- a/pkg/dev_compiler/lib/src/codegen/js_codegen.dart
+++ b/pkg/dev_compiler/lib/src/codegen/js_codegen.dart
@@ -29,7 +29,9 @@ import 'package:dev_compiler/src/info.dart';
 import 'package:dev_compiler/src/options.dart';
 import 'package:dev_compiler/src/report.dart';
 import 'package:dev_compiler/src/utils.dart';
+
 import 'code_generator.dart';
+import 'js_names.dart';
 
 bool _isAnnotationType(Annotation m, String name) => m.name.name == name;
 
@@ -53,7 +55,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
   /// The variable for the target of the current `..` cascade expression.
   SimpleIdentifier _cascadeTarget;
   /// The variable for the current catch clause
-  String _catchParameter;
+  SimpleIdentifier _catchParameter;
 
   ClassDeclaration currentClass;
   ConstantEvaluator _constEvaluator;
@@ -78,6 +80,13 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
 
   LibraryElement get currentLibrary => libraryInfo.library;
 
+  /// The name for the library's exports inside itself.
+  /// This much be a constant because we interpolate it into template strings,
+  /// and otherwise it would break caching for them.
+  /// `exports` was chosen as the most similar to ES module patterns.
+  final JSTemporary _exportsVar = new JSTemporary('exports');
+  final JSTemporary _namedArgTemp = new JSTemporary('opts');
+
   JS.Program emitLibrary(LibraryUnit library) {
     var jsDefaultValue = '{}';
     var unit = library.library;
@@ -113,7 +122,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
 
     // TODO(jmesserly): make these immutable in JS?
     for (var name in _exports) {
-      body.add(js.statement('$_EXPORTS.# = #;', [name, name]));
+      body.add(js.statement('#.# = #;', [_exportsVar, name, name]));
     }
 
     var name = jsLibraryName(libraryInfo.library);
@@ -121,13 +130,18 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
     var defaultValue = js.call(jsDefaultValue);
     return new JS.Program([
       js.statement('var #;', name),
-      js.statement("(function($_EXPORTS) { 'use strict'; #; })(# || (# = #));",
-          [body, name, name, defaultValue])
+      js.statement("(function(#) { 'use strict'; #; })(# || (# = #));", [
+        _exportsVar,
+        body,
+        name,
+        name,
+        defaultValue
+      ])
     ]);
   }
 
-  JS.Statement _initPrivateSymbol(String name) =>
-      js.statement('let # = $_SYMBOL(#);', [name, js.string(name, "'")]);
+  JS.Statement _initPrivateSymbol(String name) => js.statement(
+      'let # = $_SYMBOL(#);', [new JSTemporary(name), js.string(name, "'")]);
 
   // TODO(jmesserly): this is a temporary workaround for `Symbol` in core,
   // until we have better name tracking.
@@ -315,7 +329,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
 
       var target = genericName;
       if (_needQualifiedName(classElem)) {
-        target = js.call('#.#', [_EXPORTS, genericName]);
+        target = js.call('#.#', [_exportsVar, genericName]);
       }
       genericInst = js.call('#(#)', [target, dynamicArgs]);
     }
@@ -329,7 +343,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
         return js.statement(
             '{ #; dart.defineLazyClassGeneric(#, #, { get: # }); }', [
           genericDef,
-          _EXPORTS,
+          _exportsVar,
           js.string(name, "'"),
           genericName
         ]);
@@ -337,7 +351,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
 
       return js.statement(
           'dart.defineLazyClass(#, { get #() { #; return #; } });', [
-        _EXPORTS,
+        _exportsVar,
         _propertyName(name),
         body,
         name
@@ -561,7 +575,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
         }
       }
     }
-    var lazy = _emitLazyFields(name, lazyStatics);
+    var lazy = _emitLazyFields(new JS.Identifier(name), lazyStatics);
     if (lazy != null) body.add(lazy);
     return _statement(body);
   }
@@ -801,9 +815,12 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
       var name = param.identifier.name;
 
       if (param.kind == ParameterKind.NAMED) {
-        body.add(js.statement('let # = opt\$ && # in opt\$ ? opt\$.# : #;', [
+        body.add(js.statement('let # = # && # in # ? #.# : #;', [
           name,
+          _namedArgTemp,
           js.string(name, "'"),
+          _namedArgTemp,
+          _namedArgTemp,
           name,
           _defaultParamValue(param),
         ]));
@@ -934,8 +951,13 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
     } else if (variable is ConstFieldElementImpl) {
       var className = (variable.enclosingElement as ClassElement).name;
       return js.call('#.#', [className, name]);
-    } else if (e is ParameterElement && e.isInitializingFormal) {
-      name = _fieldParameterName(name);
+    } else if (e is ParameterElement && e.isInitializingFormal && e.isPrivate) {
+      /// Rename private names so they don't shadow the private field symbol.
+      /// The renamer would handle this, but it would prefer to rename the
+      /// temporary used for the private symbol. Instead rename the parameter.
+      return new JSTemporary('${name.substring(1)}');
+    } else if (_isTemporary(e)) {
+      return new JSTemporary(e.name);
     }
     return new JS.Identifier(name);
   }
@@ -1162,7 +1184,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
     var result = <JS.Identifier>[];
     for (FormalParameter param in node.parameters) {
       if (param.kind == ParameterKind.NAMED) {
-        result.add(new JS.Identifier(r'opt$'));
+        result.add(_namedArgTemp);
         break;
       }
       result.add(_visit(param));
@@ -1265,13 +1287,13 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
   }
 
   void _flushLazyFields(List<JS.Statement> body) {
-    var code = _emitLazyFields(_EXPORTS, _lazyFields);
+    var code = _emitLazyFields(_exportsVar, _lazyFields);
     if (code != null) body.add(code);
     _lazyFields.clear();
   }
 
   JS.Statement _emitLazyFields(
-      String objExpr, List<VariableDeclaration> fields) {
+      JS.Expression objExpr, List<VariableDeclaration> fields) {
     if (fields.isEmpty) return null;
 
     var methods = [];
@@ -1294,8 +1316,10 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
 
   void _flushLibraryProperties(List<JS.Statement> body) {
     if (_properties.isEmpty) return;
-    body.add(js.statement('dart.copyProperties($_EXPORTS, { # });',
-        [_properties.map(_emitTopLevelProperty)]));
+    body.add(js.statement('dart.copyProperties(#, { # });', [
+      _exportsVar,
+      _properties.map(_emitTopLevelProperty)
+    ]));
     _properties.clear();
   }
 
@@ -1466,17 +1490,26 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
 
   // TODO(jmesserly, vsm): Refactor this logic.
   SimpleIdentifier _createTemporary(String name, DartType type) {
+    // We use an invalid source location to signal that this is a temporary.
+    // See [_isTemporary].
+    // TODO(jmesserly): alternatives are
+    // * (ab)use Element.isSynthetic, which isn't currently used for
+    //   LocalVariableElementImpl, so we could repurpose to mean "temp".
+    // * add a new property to LocalVariableElementImpl.
+    // * create a new subtype of LocalVariableElementImpl to mark a temp.
     var id =
-        new SimpleIdentifier(new StringToken(TokenType.IDENTIFIER, name, 0));
+        new SimpleIdentifier(new StringToken(TokenType.IDENTIFIER, name, -1));
     id.staticElement = new LocalVariableElementImpl.forNode(id);
     id.staticType = type;
     return id;
   }
 
+  bool _isTemporary(Element node) => node.nameOffset == -1;
+
   JS.Expression _emitPostfixIncrement(Expression expr, Token op) {
     var type = rules.getStaticType(expr);
     assert(type != null);
-    var tmp = _createTemporary('\$tmp', type);
+    var tmp = _createTemporary('x', type);
 
     // Increment and write
     var one = AstBuilder.integerLiteral(1);
@@ -1588,20 +1621,16 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
       // remains valid in an expression context.
       // TODO(jmesserly): need a better way to handle temps.
       // TODO(jmesserly): special case for parent is ExpressionStatement?
-      _cascadeTarget =
-          new SimpleIdentifier(new StringToken(TokenType.IDENTIFIER, '_', 0));
-      _cascadeTarget.staticElement =
-          new LocalVariableElementImpl.forNode(_cascadeTarget);
-      _cascadeTarget.staticType = node.target.staticType;
+      _cascadeTarget = _createTemporary('_', node.target.staticType);
 
       var body = _visitList(node.cascadeSections);
       if (node.parent is! ExpressionStatement) {
-        body.add(js.statement('return #;', _cascadeTarget.name));
+        body.add(js.statement('return #;', _visit(_cascadeTarget)));
       }
 
       var bindThis = _maybeBindThis(node.cascadeSections);
       result = js.call('((#) => { # })$bindThis(#)', [
-        _cascadeTarget.name,
+        _visit(_cascadeTarget),
         body,
         _visit(node.target)
       ]);
@@ -1638,15 +1667,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
 
   @override
   visitFormalParameter(FormalParameter node) =>
-      new JS.Identifier(node.identifier.name);
-
-  @override
-  visitFieldFormalParameter(FieldFormalParameter node) =>
-      new JS.Identifier(_fieldParameterName(node.identifier.name));
-
-  /// Rename private names so they don't shadow the private field symbol.
-  // TODO(jmesserly): replace this ad-hoc rename with a general strategy.
-  _fieldParameterName(name) => name.startsWith('_') ? '\$$name' : name;
+      visitSimpleIdentifier(node.identifier);
 
   @override
   JS.This visitThisExpression(ThisExpression node) => new JS.This();
@@ -1719,9 +1740,9 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
   @override
   visitRethrowExpression(RethrowExpression node) {
     if (node.parent is ExpressionStatement) {
-      return js.statement('throw #;', _catchParameter);
+      return js.statement('throw #;', _visit(_catchParameter));
     } else {
-      return js.call('dart.throw_(#)', _catchParameter);
+      return js.call('dart.throw_(#)', _visit(_catchParameter));
     }
   }
 
@@ -1782,21 +1803,34 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
     // TODO(jmesserly): need a better way to get a temporary variable.
     // This could incorrectly shadow a user's name.
     var savedCatch = _catchParameter;
-    _catchParameter = '\$e';
 
     if (clauses.length == 1) {
       // Special case for a single catch.
-      var clause = clauses.single;
-      if (clause.exceptionParameter != null) {
-        _catchParameter = clause.exceptionParameter.name;
-      }
+      _catchParameter = clauses.single.exceptionParameter;
+    } else {
+      _catchParameter = _createTemporary('e', rules.provider.dynamicType);
+    }
+
+    JS.Statement catchBody = null;
+    for (var clause in clauses.reversed) {
+      catchBody = _catchClauseGuard(clause, catchBody);
     }
 
-    var catchVarDecl = new JS.Identifier(_catchParameter);
-    var catchBody = new JS.Block(_visitList(clauses));
+    var catchVarDecl = _visit(_catchParameter);
     _catchParameter = savedCatch;
+    return new JS.Catch(catchVarDecl, new JS.Block([catchBody]));
+  }
+
+  JS.Statement _catchClauseGuard(CatchClause clause, JS.Statement otherwise) {
+    var then = visitCatchClause(clause);
+
+    // Discard following clauses, if any, as they are unreachable.
+    if (clause.exceptionType == null) return then;
 
-    return new JS.Catch(catchVarDecl, catchBody);
+    return new JS.If(js.call('dart.is(#, #)', [
+      _visit(_catchParameter),
+      _emitTypeName(clause.exceptionType.type),
+    ]), then, otherwise);
   }
 
   JS.Statement _statement(Iterable stmts) {
@@ -1807,6 +1841,8 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
     return new JS.Block(s);
   }
 
+  /// Visits the catch clause body. This skips the exception type guard, if any.
+  /// That is handled in [_visitCatch].
   @override
   JS.Statement visitCatchClause(CatchClause node) {
     var body = [];
@@ -1814,11 +1850,10 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
     var savedCatch = _catchParameter;
     if (node.catchKeyword != null) {
       var name = node.exceptionParameter;
-      if (name != null && name.name != _catchParameter) {
-        var decl = new JS.Identifier(name.name);
-        decl.sourceInformation = name;
-        body.add(js.statement('let # = #;', [decl, _catchParameter]));
-        _catchParameter = name.name;
+      if (name != null && name != _catchParameter) {
+        body.add(js.statement(
+            'let # = #;', [_visit(name), _visit(_catchParameter)]));
+        _catchParameter = name;
       }
       if (node.stackTraceParameter != null) {
         var stackVar = node.stackTraceParameter.name;
@@ -1829,15 +1864,6 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
 
     body.add(_visit(node.body));
     _catchParameter = savedCatch;
-
-    if (node.exceptionType != null) {
-      return js.statement('if (dart.is(#, #)) #;', [
-        _catchParameter,
-        _emitTypeName(node.exceptionType.type),
-        _statement(body)
-      ]);
-    }
-
     return _statement(body);
   }
 
@@ -2071,7 +2097,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
   JS.Expression _jsMemberName(String name, {bool unary: false}) {
     if (name.startsWith('_')) {
       if (_privateNames.add(name)) _pendingPrivateNames.add(name);
-      return new JS.Identifier(name);
+      return new JSTemporary(name);
     }
     if (name == '[]') {
       name = 'get';
@@ -2092,9 +2118,9 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
   /// Choose a canonical name from the library element.
   /// This never uses the library's name (the identifier in the `library`
   /// declaration) as it doesn't have any meaningful rules enforced.
-  String _libraryName(LibraryElement library) {
-    if (library == libraryInfo.library) return _EXPORTS;
-    return jsLibraryName(library);
+  JS.Identifier _libraryName(LibraryElement library) {
+    if (library == libraryInfo.library) return _exportsVar;
+    return new JS.Identifier(jsLibraryName(library));
   }
 
   String _maybeBindThis(node) {
@@ -2105,12 +2131,6 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
     return visitor._bindThis ? '.bind(this)' : '';
   }
 
-  /// The name for the library's exports inside itself.
-  /// This much be a constant because we interpolate it into template strings,
-  /// and otherwise it would break caching for them.
-  /// `exports` was chosen as the most similar to ES module patterns.
-  static const String _EXPORTS = 'exports';
-
   static bool _needsImplicitThis(Element e) =>
       e is PropertyAccessorElement && !e.variable.isStatic ||
           e is ClassMemberElement && !e.isStatic && e is! ConstructorElement;
@@ -2218,8 +2238,8 @@ class JSGenerator extends CodeGenerator {
 }
 
 void _writeNode(JS.JavaScriptPrintingContext context, JS.Node node) {
-  var opts = new JS.JavaScriptPrintingOptions(avoidKeywordsInIdentifiers: true);
-  node.accept(new JS.Printer(opts, context));
+  var opts = new JS.JavaScriptPrintingOptions(allowKeywordsInProperties: true);
+  node.accept(new JS.Printer(opts, context, localNamer: new JSNamer(node)));
 }
 
 /// This is a debugging helper to print a JS node.
diff --git a/pkg/dev_compiler/lib/src/codegen/js_names.dart b/pkg/dev_compiler/lib/src/codegen/js_names.dart
new file mode 100644
index 000000000000..58d750718a41
--- /dev/null
+++ b/pkg/dev_compiler/lib/src/codegen/js_names.dart
@@ -0,0 +1,81 @@
+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library dev_compiler.src.codegen.js_names;
+
+import 'package:dev_compiler/src/js/js_ast.dart';
+import 'package:dev_compiler/src/js/keywords.dart';
+
+/// Marker subclass for temporary variables.
+/// We treat these as being in a different scope from other identifiers, and
+/// rename them so they don't collide. See [JSNamer].
+// TODO(jmesserly): move into js_ast? add a boolean to Identifier?
+class JSTemporary extends Identifier {
+  JSTemporary(String name) : super(name);
+}
+
+/// This class has two purposes:
+/// * rename JS identifiers to avoid keywords.
+/// * rename temporary variables to avoid colliding with user-specified names.
+///
+/// We use a very simple algorithm:
+/// * collect all names
+/// * visit the tree, choosing unique names for things we need to rename
+///
+/// We assume the scoping is already correct (if the isTemporary bit is
+/// considered as part of the name), so we can do both of these renames
+/// globally, with no regard to where the name was declared or which precise
+/// identifier it was bound to.
+// TODO(jmesserly): some future transforms, like ES6->5, might want a name bound
+// tree, but we can defer that until needed.
+class JSNamer extends LocalNamer {
+  final usedNames = new Set<String>();
+  final renames = new Map<String, String>();
+
+  JSNamer(Node node) {
+    node.accept(new _NameCollector(usedNames));
+  }
+
+  String getName(Identifier node) {
+    var name = node.name;
+    if (node is JSTemporary) {
+      return _rename(name, valid: true);
+    } else if (isJsKeyword(name)) {
+      return _rename(name, valid: false);
+    }
+    return name;
+  }
+
+  String _rename(String name, {bool valid}) {
+    var candidate = renames[name];
+    if (candidate != null) return candidate;
+
+    // Try to use the temp's name, otherwise rename.
+    if (valid && usedNames.add(name)) {
+      candidate = name;
+    } else {
+      // This assumes that collisions are rare, hence linear search.
+      // If collisions become common we need a better search.
+      // TODO(jmesserly): what's the most readable scheme here? Maybe 1-letter
+      // names in some cases?
+      candidate = name == 'function' ? 'func' : '${name}\$';
+      for (int i = 0; !usedNames.add(candidate); i++) {
+        candidate = '${name}\$$i';
+      }
+    }
+    return renames[name] = candidate;
+  }
+
+  void enterScope(Node node) {}
+  void leaveScope() {}
+}
+
+/// Collects all names used in the visited tree.
+class _NameCollector extends BaseVisitor {
+  final Set<String> names;
+  _NameCollector(this.names);
+  visitIdentifier(Identifier node) {
+    if (node is! JSTemporary) names.add(node.name);
+  }
+}
diff --git a/pkg/dev_compiler/lib/src/js/js_ast.dart b/pkg/dev_compiler/lib/src/js/js_ast.dart
index 121ac7f8e4c6..ee8289ecf2df 100644
--- a/pkg/dev_compiler/lib/src/js/js_ast.dart
+++ b/pkg/dev_compiler/lib/src/js/js_ast.dart
@@ -6,7 +6,6 @@ library js_ast;
 
 import 'precedence.dart';
 import 'characters.dart' as charCodes;
-import 'keywords.dart';
 
 part 'nodes.dart';
 part 'builder.dart';
diff --git a/pkg/dev_compiler/lib/src/js/printer.dart b/pkg/dev_compiler/lib/src/js/printer.dart
index 0e92ed5e224e..90cba8e47206 100644
--- a/pkg/dev_compiler/lib/src/js/printer.dart
+++ b/pkg/dev_compiler/lib/src/js/printer.dart
@@ -9,13 +9,17 @@ class JavaScriptPrintingOptions {
   final bool shouldCompressOutput;
   final bool minifyLocalVariables;
   final bool preferSemicolonToNewlineInMinifiedOutput;
-  final bool avoidKeywordsInIdentifiers;
+
+
+  /// True to allow keywords in properties, such as `obj.var` or `obj.function`
+  /// Modern JS engines support this.
+  final bool allowKeywordsInProperties;
 
   JavaScriptPrintingOptions(
       {this.shouldCompressOutput: false,
        this.minifyLocalVariables: false,
        this.preferSemicolonToNewlineInMinifiedOutput: false,
-       this.avoidKeywordsInIdentifiers: false});
+       this.allowKeywordsInProperties: false});
 }
 
 
@@ -68,17 +72,18 @@ class Printer implements NodeVisitor {
   static final expressionContinuationRegExp = new RegExp(r'^[-+([]');
 
   Printer(JavaScriptPrintingOptions options,
-          JavaScriptPrintingContext context)
+          JavaScriptPrintingContext context,
+          {LocalNamer localNamer})
       : options = options,
         context = context,
         shouldCompressOutput = options.shouldCompressOutput,
         danglingElseVisitor = new DanglingElseVisitor(context),
-        localNamer = determineRenamer(options.shouldCompressOutput,
-                                      options.minifyLocalVariables);
+        localNamer = determineRenamer(localNamer, options);
 
-  static LocalNamer determineRenamer(bool shouldCompressOutput,
-                                     bool allowVariableMinification) {
-    return (shouldCompressOutput && allowVariableMinification)
+  static LocalNamer determineRenamer(LocalNamer localNamer,
+                                     JavaScriptPrintingOptions options) {
+    if (localNamer != null) return localNamer;
+    return (options.shouldCompressOutput && options.minifyLocalVariables)
         ? new MinifyRenamer() : new IdentityNamer();
   }
 
@@ -778,8 +783,8 @@ class Printer implements NodeVisitor {
     out("super");
   }
 
-  visitIdentifier(Identifier param) {
-    out(localNamer.getName(param.name));
+  visitIdentifier(Identifier node) {
+    out(localNamer.getName(node));
   }
 
   bool isDigit(int charCode) {
@@ -801,14 +806,10 @@ class Printer implements NodeVisitor {
       }
     }
 
-    if (options.avoidKeywordsInIdentifiers) {
-      return !isJsKeyword(field.substring(1, field.length - 1));
-    } else {
-      // TODO(floitsch): normally we should also check that the field is not a
-      // reserved word.  We don't generate fields with reserved word names except
-      // for 'super'.
-      return field != '"super"';
-    }
+    // TODO(floitsch): normally we should also check that the field is not a
+    // reserved word.  We don't generate fields with reserved word names except
+    // for 'super'.
+    return options.allowKeywordsInProperties || field != '"super"';
   }
 
   visitAccess(PropertyAccess access) {
@@ -1241,14 +1242,14 @@ class DanglingElseVisitor extends BaseVisitor<bool> {
 
 
 abstract class LocalNamer {
-  String getName(String oldName);
+  String getName(Identifier node);
   void enterScope(Node node);
   void leaveScope();
 }
 
 
 class IdentityNamer implements LocalNamer {
-  String getName(String oldName) => oldName;
+  String getName(Identifier node) => node.name;
   void enterScope(Node node) {}
   void leaveScope() {}
 }
@@ -1277,7 +1278,8 @@ class MinifyRenamer implements LocalNamer {
     parameterNumber = parameterNumberStack.removeLast();
   }
 
-  String getName(String oldName) {
+  String getName(Identifier node) {
+    String oldName = node.name;
     // Go from inner scope to outer looking for mapping of name.
     for (int i = maps.length - 1; i >= 0; i--) {
       var map = maps[i];
diff --git a/pkg/dev_compiler/test/codegen/expect/constructors.js b/pkg/dev_compiler/test/codegen/expect/constructors.js
index 2b1df9b0cf0c..853a29316f27 100644
--- a/pkg/dev_compiler/test/codegen/expect/constructors.js
+++ b/pkg/dev_compiler/test/codegen/expect/constructors.js
@@ -42,8 +42,8 @@ var constructors;
     }
   }
   class H extends core.Object {
-    H(opt$) {
-      let p1 = opt$ && 'p1' in opt$ ? opt$.p1 : null;
+    H(opts) {
+      let p1 = opts && 'p1' in opts ? opts.p1 : null;
     }
   }
   class I extends core.Object {
diff --git a/pkg/dev_compiler/test/codegen/expect/methods.js b/pkg/dev_compiler/test/codegen/expect/methods.js
index ea96ac0df6e3..3fe7d7e5f013 100644
--- a/pkg/dev_compiler/test/codegen/expect/methods.js
+++ b/pkg/dev_compiler/test/codegen/expect/methods.js
@@ -22,12 +22,12 @@ var methods;
         b = 0;
       return b;
     }
-    w(a, opt$) {
-      let b = opt$ && 'b' in opt$ ? opt$.b : null;
+    w(a, opts) {
+      let b = opts && 'b' in opts ? opts.b : null;
       return dart.notNull(a) + dart.notNull(b);
     }
-    ww(a, opt$) {
-      let b = opt$ && 'b' in opt$ ? opt$.b : 0;
+    ww(a, opts) {
+      let b = opts && 'b' in opts ? opts.b : 0;
       return dart.notNull(a) + dart.notNull(b);
     }
     get a() {
diff --git a/pkg/dev_compiler/test/codegen/expect/names.js b/pkg/dev_compiler/test/codegen/expect/names.js
new file mode 100644
index 000000000000..ac268d4e3510
--- /dev/null
+++ b/pkg/dev_compiler/test/codegen/expect/names.js
@@ -0,0 +1,24 @@
+var names;
+(function(exports) {
+  'use strict';
+  exports.exports = 42;
+  let _foo$ = Symbol('_foo');
+  class Foo extends core.Object {
+    [_foo$]() {
+      return 123;
+    }
+  }
+  // Function _foo: () → dynamic
+  function _foo() {
+    return 456;
+  }
+  // Function main: () → dynamic
+  function main() {
+    core.print(exports.exports);
+    core.print(new Foo()._foo());
+    core.print(_foo());
+  }
+  // Exports:
+  exports.Foo = Foo;
+  exports.main = main;
+})(names || (names = {}));
diff --git a/pkg/dev_compiler/test/codegen/expect/names.txt b/pkg/dev_compiler/test/codegen/expect/names.txt
new file mode 100644
index 000000000000..90fba0c957a4
--- /dev/null
+++ b/pkg/dev_compiler/test/codegen/expect/names.txt
@@ -0,0 +1 @@
+// Messages from compiling names.dart
diff --git a/pkg/dev_compiler/test/codegen/expect/server_mode/html_input.html b/pkg/dev_compiler/test/codegen/expect/server_mode/html_input.html
index 11f6e7f70c3e..7f6507583038 100644
--- a/pkg/dev_compiler/test/codegen/expect/server_mode/html_input.html
+++ b/pkg/dev_compiler/test/codegen/expect/server_mode/html_input.html
@@ -1,7 +1,7 @@
 <html><head></head><body>
 <script src="cached/c947f9f732203b97dd2882e63da78dbe/dev_compiler/runtime/harmony_feature_check.js"></script>
 <script src="cached/4615119c209e4a6985a41cff7647d1c5/dev_compiler/runtime/dart_runtime.js"></script>
-<script src="cached/5ffe2b672ea94c7fe06e7b188f7dac10/dev_compiler/runtime/dart/core.js"></script>
+<script src="cached/c1f8bdd710eb9ba92315774d7a62d81b/dev_compiler/runtime/dart/core.js"></script>
 <script src="cached/b846e240bec12226bbe7dcccfdd3fdf6/dev_compiler/runtime/dart/math.js"></script>
 <script src="cached/c36af93826f645c97ae65b44badd998b/dev_compiler/runtime/messages_widget.js"></script>
 <link rel="stylesheet" href="cached/307a7ef1e0cd0544d55c6f768f5e3886/dev_compiler/runtime/messages.css">
diff --git a/pkg/dev_compiler/test/codegen/expect/sunflower/dom.js b/pkg/dev_compiler/test/codegen/expect/sunflower/dom.js
index ea7f264505db..62d83cdbe913 100644
--- a/pkg/dev_compiler/test/codegen/expect/sunflower/dom.js
+++ b/pkg/dev_compiler/test/codegen/expect/sunflower/dom.js
@@ -2,8 +2,8 @@ var dom;
 (function(exports) {
   'use strict';
   class JsName extends core.Object {
-    JsName(opt$) {
-      let name = opt$ && 'name' in opt$ ? opt$.name : null;
+    JsName(opts) {
+      let name = opts && 'name' in opts ? opts.name : null;
       this.name = name;
     }
   }
diff --git a/pkg/dev_compiler/test/codegen/expect/try_catch.js b/pkg/dev_compiler/test/codegen/expect/try_catch.js
index 9ad17ef3a632..8a5d5b8c48a6 100644
--- a/pkg/dev_compiler/test/codegen/expect/try_catch.js
+++ b/pkg/dev_compiler/test/codegen/expect/try_catch.js
@@ -1,21 +1,39 @@
 var try_catch;
 (function(exports) {
   'use strict';
-  // Function main: () → dynamic
-  function main() {
+  // Function foo: () → dynamic
+  function foo() {
     try {
       throw "hi there";
-    } catch ($e) {
-      if (dart.is($e, core.String)) {
-        let e = $e;
+    } catch (e$) {
+      if (dart.is(e$, core.String)) {
+        let e = e$;
+        let t = dart.stackTrace(e);
+      } else {
+        let e = e$;
         let t = dart.stackTrace(e);
+        throw e;
       }
-      let e = $e;
+    }
+
+  }
+  // Function bar: () → dynamic
+  function bar() {
+    try {
+      throw "hi there";
+    } catch (e$) {
+      let e = e$;
       let t = dart.stackTrace(e);
-      throw e;
     }
 
   }
+  // Function main: () → dynamic
+  function main() {
+    foo();
+    bar();
+  }
   // Exports:
+  exports.foo = foo;
+  exports.bar = bar;
   exports.main = main;
 })(try_catch || (try_catch = {}));
diff --git a/pkg/dev_compiler/test/codegen/names.dart b/pkg/dev_compiler/test/codegen/names.dart
new file mode 100644
index 000000000000..127655eb2429
--- /dev/null
+++ b/pkg/dev_compiler/test/codegen/names.dart
@@ -0,0 +1,17 @@
+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+var exports = 42;
+
+class Foo {
+  _foo() => 123;
+}
+
+_foo() => 456;
+
+main() {
+  print(exports);
+  print(new Foo()._foo());
+  print(_foo());
+}
diff --git a/pkg/dev_compiler/test/codegen/try_catch.dart b/pkg/dev_compiler/test/codegen/try_catch.dart
index c67493f9c19e..844d7f24d1e5 100644
--- a/pkg/dev_compiler/test/codegen/try_catch.dart
+++ b/pkg/dev_compiler/test/codegen/try_catch.dart
@@ -1,4 +1,8 @@
-main() {
+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+foo() {
   try {
     throw "hi there";
   } on String catch (e, t) {
@@ -6,4 +10,16 @@ main() {
     rethrow;
   }
 }
-
+bar() {
+  try {
+    throw "hi there";
+  } catch (e, t) {
+  } on String catch (e, t) {
+    // unreachable
+    rethrow;
+  }
+}
+main() {
+  foo();
+  bar();
+}