Remove StreamSink(replaced by EventSink) and make IOSink extend EventSink.

sdk/lib/isolate/isolate_stream.dart

 // Copyright (c) 2012, 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.
 
 part of dart.isolate;
 
 /**
  * The initial [IsolateStream] available by default for this isolate. This
  * [IsolateStream] is created automatically and it is commonly used to establish
  * the first communication between isolates (see [streamSpawnFunction] and
@@ skipping 76 matching lines @@
   }
 }
 
 /**
  * [IsolateSink]s represent the feed for [IsolateStream]s. Any message written
  * to [this] is delivered to its respective [IsolateStream]. [IsolateSink]s are
  * created by [MessageBox]es.
  *
  * [IsolateSink]s can be transmitted to other isolates.
  */
-abstract class IsolateSink extends StreamSink<dynamic> {
-  // TODO(8997): Implement EventSink instead.
+abstract class IsolateSink extends EventSink<dynamic> {
   // TODO(floitsch): Actually it should be a StreamSink (being able to flow-
   // control).
 
   /**
    * Sends an asynchronous [message] to the linked [IsolateStream]. The message
    * is copied to the receiving isolate.
    *
    * The content of [message] can be: primitive values (null, num, bool, double,
    * String), instances of [IsolateSink]s, and lists and maps whose elements are
    * any of these. List and maps are also allowed to be cyclic.
@@ skipping 33 matching lines @@
  * default stream.
  *
  * The optional [unhandledExceptionCallback] argument is invoked whenever an
  * exception inside the isolate is unhandled. It can be seen as a big
  * `try/catch` around everything that is executed inside the isolate. The
  * callback should return `true` when it was able to handled the exception.
  */
 external IsolateSink streamSpawnFunction(
     void topLevelFunction(),
     [bool unhandledExceptionCallback(IsolateUnhandledException e)]);