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

sdk/lib/async/stream_controller.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.async;
 
 // -------------------------------------------------------------------
 // Controller for creating and adding events to a stream.
 // -------------------------------------------------------------------
 
@@ skipping 28 matching lines @@
  * Whether to invoke a callback depends only on the state before and after
  * a stream action, for example firing an event. If the state changes multiple
  * times during the action, and then ends up in the same state as before, no
  * callback is performed.
  *
  * If listeners are added after the stream has completed (sent a "done" event),
  * the listeners will be sent a "done" event eventually, but they won't affect
  * the stream at all, and won't trigger callbacks. From the controller's point
  * of view, the stream is completely inert when has completed.
  */
-class StreamController<T> extends StreamSink<T> {
-  // TODO(8997): Implement EventSink instead.
+class StreamController<T> extends EventSink<T> {
   final _StreamImpl<T> stream;
 
   /**
    * A controller with a broadcast [stream]..
    *
    * The [onPauseStateChange] function is called when the stream becomes
    * paused or resumes after being paused. The current pause state can
    * be read from [isPaused]. Ignored if [:null:].
    *
    * The [onSubscriptionStateChange] function is called when the stream
@@ skipping 127 matching lines @@
   void _onPauseStateChange() {
     if (_pauseHandler != null) {
       try {
         _pauseHandler();
       } catch (e, s) {
         new AsyncError(e, s).throwDelayed();
       }
     }
   }
 }