dart2js: size / readability low hanging fruit #2: generate || and &&

[rakudrama]

|| and && expand to huge amounts of code.
Code with this structure should be recognized and collapsed to something more readable.

Example:

Isolate.$defineClass("HashMapImplementation", "Object", ["_numberOfDeleted", "_numberOfEntries", "_loadLimit", "_values", "_keys?"], {
 ...
 forEach$1: function(f) {
  var length$ = $.get$length(this._keys);
  for (var i = 0; $.ltB(i, length$); i = i + 1) {
    var key = $.index(this._keys, i);
    var t0 = !(key === (void 0));
    if (t0) {
      var t1 = !(key === $.CTC21);
    } else {
      t1 = t0;
    }
    if (t1) {
      f.$call$2(key, $.index(this._values, i));
    } else {
    }
  }
 },

--->
 forEach$1: function(f) {
  var length$ = $.get$length(this._keys);
  for (var i = 0; $.ltB(i, length$); i = i + 1) {
    var key = $.index(this._keys, i);
    if (!(key === (void 0)) &&
        !(key === $.CTC21)) {
      f.$call$2(key, $.index(this._values, i));
    }
  }
 },

For comparison, frog was much closer to the original (the weird comparison against const$0000 is because (1) frog allows null and undefined for Dart null and (2) frog doesn't know const$0000 is non-null).

HashMapImplementation.prototype.forEach = function(f) {
  var length = this._keys.get$length();
  for (var i = (0);
   i < length; i++) {
    var key = this._keys.$index(i);
    if ((null != key) && ((null == key ? null != (const$0000) : key !== const$0000))) {
      f(key, this._values.$index(i));
    }
  }
}

[kasperl]

Set owner to ngeoffray@google.com.
Added Accepted label.

[DartBot]

This comment was originally written by ngeoffray@google.com

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Fixed in https://chromiumcodereview.appspot.com//10495013

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Added Fixed label.

[rakudrama]

Nice!

Any idea why this one didn't reduce:

$._isWhitespace = function(c) {
  $0:{
    if (!(32 === c)) {
      if (!(9 === c)) {
        var t1 = 10 === c || 13 === c;
      } else {
        t1 = true;
      }
    } else {
      t1 = true;
    }
    if (t1) {
      return true;
    }
  }
  return false;
};

[DartBot]

This comment was originally written by ngeoffray@google.com

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That's because we're not recognizing nested logical operations. Fix under review: https://chromiumcodereview.appspot.com/10539042