Make StreamController be a StreamSink, not just an EventSink.

sdk/lib/async/stream.dart

Index: sdk/lib/async/stream.dart
diff --git a/sdk/lib/async/stream.dart b/sdk/lib/async/stream.dart
index 43697ecc4ff4bd220422cddf605f09d3d0a869bd..d9a0a8fda91f426568a680b2993adcd9b294db2a 100644
--- a/sdk/lib/async/stream.dart
+++ b/sdk/lib/async/stream.dart
@@ -920,19 +920,6 @@ class StreamView<T> extends Stream<T> {
   }
 }
 
-/**
- * [EventSink] wrapper that only exposes the [EventSink] interface.
- */
-class _EventSinkView<T> extends EventSink<T> {
-  final EventSink<T> _sink;
-
-  _EventSinkView(this._sink);
-
-  void add(T value) { _sink.add(value); }
-  void addError(error) { _sink.addError(error); }
-  void close() { _sink.close(); }
-}
-
 
 /**
  * The target of a [Stream.pipe] call.