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

sdk/lib/io/io_sink.dart

Index: sdk/lib/io/io_sink.dart
diff --git a/sdk/lib/io/io_sink.dart b/sdk/lib/io/io_sink.dart
index 685024cd09715f2e00d026502865cae1b76c73cb..794095e68d56132899f2b13816857e86a9b77cbc 100644
--- a/sdk/lib/io/io_sink.dart
+++ b/sdk/lib/io/io_sink.dart
@@ -8,14 +8,15 @@ part of dart.io;
  * Helper class to wrap a [StreamConsumer<List<int>, T>] and provide
  * utility functions for writing to the StreamConsumer directly. The
  * [IOSink] buffers the input given by [write], [writeAll], [writeln],
- * [writeCharCode] and [writeBytes] and will delay a [consume] or
+ * [writeCharCode] and [add] and will delay a [consume] or
  * [writeStream] until the buffer is flushed.
  *
  * When the [IOSink] is bound to a stream (through either [consume]
  * or [writeStream]) any call to the [IOSink] will throw a
  * [StateError].
  */
-abstract class IOSink<T> implements StreamConsumer<List<int>, T>, StringSink {
+abstract class IOSink<T>
+    implements StreamConsumer<List<int>, T>, StringSink, EventSink<List<int>> {
   factory IOSink(StreamConsumer<List<int>, T> target,
                  {Encoding encoding: Encoding.UTF_8})
       => new _IOSinkImpl(target, encoding);
@@ -29,7 +30,12 @@ abstract class IOSink<T> implements StreamConsumer<List<int>, T>, StringSink {
   /**
    * Writes the bytes uninterpreted to the consumer.
    */
-  void writeBytes(List<int> data);
+  void add(List<int> data);
+
+  /**
+   * Writes an error to the consumer.
+   */
+  void addError(AsyncError error);
 
   /**
    * Provide functionality for piping to the [IOSink].
@@ -100,7 +106,7 @@ class _IOSinkImpl<T> implements IOSink<T> {
       }
     }
     if (string.isEmpty) return;
-    writeBytes(_encodeString(string, _encoding));
+    add(_encodeString(string, _encoding));
   }
 
   void writeAll(Iterable objects, [String separator = ""]) {
@@ -128,13 +134,20 @@ class _IOSinkImpl<T> implements IOSink<T> {
     write(new String.fromCharCode(charCode));
   }
 
-  void writeBytes(List<int> data) {
+  void add(List<int> data) {
     if (_isBound) {
       throw new StateError("IOSink is already bound to a stream");
     }
     _controller.add(data);
   }
 
+  void addError(AsyncError error) {
+    if (_isBound) {
+      throw new StateError("IOSink is already bound to a stream");
+    }
+    _controller.addError(error);
+  }
+
   Future<T> consume(Stream<List<int>> stream) {
     if (_isBound) {
       throw new StateError("IOSink is already bound to a stream");