Implementation of ReadableStream pipeTo and pipeThrough

Implement the pipeTo() and pipeThrough() methods on the ReadableStream
class. They are only enabled when V8 experimental extras are, eg. when the
--enable-experimental-web-platform-features flag is used. The methods are not
visible when running without flags.

To achieve this, the methods are defined in ReadableStream.js but not
added to the global object. ReadableStreamExperimentalPipeTo.js is
executed at renderer startup time when the experimental flag is set
and simply adds the two methods to the global ReadableStream object.

This initial implementation is intentionally unoptimised. While it does
use internal APIs it won't perform any better than a polyfill using the
public APIs would. Additional optimisation work is expected after
shipping.

Also remove the failing expectations for many external/wpt/streams tests
that use piping.

serviceworker still have failing expectations due to using HTTP. When
web-platform-tests/wpt@f36afea
is rolled from upstream the failures will go away.

The upstream version of the streams/piping/multiple-propagation.js test
'Piping from an errored readable stream to a closed writable stream'
doesn't pass in Chromium . This is a known incompatibility with the
reference implementation which will be resolved by
whatwg/streams#634. This CL adds a modified
version of the test in http/tests/streams/piping which verifies the
behaviour of this implementation. I have filed http://crbug.com/684543
to track it.

BUG=668951

Review-Url: https://codereview.chromium.org/2561443004
Cr-Commit-Position: refs/heads/master@{#446358}

.gn

@@ -31,8 +31,10 @@ default_args = {
     "//third_party/WebKit/Source/core/streams/CountQueuingStrategy.js",
     "//third_party/WebKit/Source/core/streams/ReadableStream.js",
   ]
-  v8_experimental_extra_library_files =
-      [ "//third_party/WebKit/Source/core/streams/WritableStream.js" ]
+  v8_experimental_extra_library_files = [
+    "//third_party/WebKit/Source/core/streams/ReadableStreamExperimentalPipeTo.js",
+    "//third_party/WebKit/Source/core/streams/WritableStream.js",
+  ]
   v8_enable_inspector = true
   v8_enable_gdbjit = false
   v8_imminent_deprecation_warnings = false

third_party/WebKit/LayoutTests/TestExpectations

@@ -1881,18 +1881,18 @@ crbug.com/626703 external/csswg-test/vendor-imports/mozilla/mozilla-central-reft
 crbug.com/626703 external/csswg-test/vendor-imports/mozilla/mozilla-central-reftests/writing-modes-3/logical-physical-mapping-001.html [ Failure ]
 crbug.com/626703 external/wpt/html/semantics/grouping-content/the-li-element/grouping-li-reftest-list-owner-menu.html [ Failure ]
 crbug.com/626703 external/wpt/html/semantics/grouping-content/the-li-element/grouping-li-reftest-list-owner-skip-no-boxes.html [ Failure ]
-crbug.com/626703 external/wpt/streams/count-queuing-strategy.https.html [ Timeout Failure ]
-crbug.com/626703 external/wpt/streams/readable-streams/bad-strategies.https.html [ Timeout Failure ]
-crbug.com/626703 external/wpt/streams/readable-streams/bad-underlying-sources.https.html [ Timeout Failure ]
-crbug.com/626703 external/wpt/streams/readable-streams/brand-checks.https.html [ Timeout Failure ]
-crbug.com/626703 external/wpt/streams/readable-streams/cancel.https.html [ Timeout Failure ]
-crbug.com/626703 external/wpt/streams/readable-streams/count-queuing-strategy-integration.https.html [ Timeout Failure ]
-crbug.com/626703 external/wpt/streams/readable-streams/garbage-collection.https.html [ Timeout Failure ]
+crbug.com/626703 external/wpt/streams/count-queuing-strategy.https.html [ Pass Timeout ]
+crbug.com/626703 external/wpt/streams/readable-streams/bad-strategies.https.html [ Pass Timeout ]
+crbug.com/626703 external/wpt/streams/readable-streams/bad-underlying-sources.https.html [ Pass Timeout ]
+crbug.com/626703 external/wpt/streams/readable-streams/brand-checks.https.html [ Pass Timeout ]
+crbug.com/626703 external/wpt/streams/readable-streams/cancel.https.html [ Pass Timeout ]
+crbug.com/626703 external/wpt/streams/readable-streams/count-queuing-strategy-integration.https.html [ Pass Timeout ]
+crbug.com/626703 external/wpt/streams/readable-streams/garbage-collection.https.html [ Pass Timeout ]
 crbug.com/626703 external/wpt/streams/readable-streams/general.https.html [ Timeout Failure ]
-crbug.com/626703 external/wpt/streams/readable-streams/pipe-through.https.html [ Timeout Failure ]
-crbug.com/626703 external/wpt/streams/readable-streams/readable-stream-reader.https.html [ Timeout Failure ]
-crbug.com/626703 external/wpt/streams/readable-streams/tee.https.html [ Timeout Failure ]
-crbug.com/626703 external/wpt/streams/readable-streams/templated.https.html [ Timeout Failure ]
+crbug.com/626703 external/wpt/streams/readable-streams/pipe-through.https.html [ Pass Timeout ]
+crbug.com/626703 external/wpt/streams/readable-streams/readable-stream-reader.https.html [ Pass Timeout ]
+crbug.com/626703 external/wpt/streams/readable-streams/tee.https.html [ Pass Timeout ]
+crbug.com/626703 external/wpt/streams/readable-streams/templated.https.html [ Pass Timeout ]
 crbug.com/626703 external/wpt/html/webappapis/idle-callbacks/callback-timeout.html [ Timeout ]
 crbug.com/626703 external/wpt/html/webappapis/idle-callbacks/callback-multiple-calls.html [ Timeout ]
 crbug.com/626703 external/wpt/html/webappapis/idle-callbacks/callback-exception.html [ Timeout ]