Add writeString method to OutputStream

runtime/bin/list_stream_impl.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.
 
 /**
  * Default implementation of [ListInputStream].
  */
 class _ListInputStream extends _BaseDataInputStream implements ListInputStream {
   _ListInputStream() : _bufferList = new _BufferList();
 
@@ skipping 24 matching lines @@
 
   void _close() {
     _streamMarkedClosed = true;
     _bufferList.clear();
   }
 
   _BufferList _bufferList;
 }
 
 
-class _ListOutputStream implements ListOutputStream {
+class _ListOutputStream extends _BaseOutputStream implements ListOutputStream {
   _ListOutputStream() : _bufferList = new _BufferList();
 
   List<int> contents() => _bufferList.readBytes(_bufferList.length);
 
   bool write(List<int> buffer, [bool copyBuffer = false]) {
     if (_streamMarkedClosed) throw new StreamException.streamClosed();
     if (copyBuffer) {
       _bufferList.add(buffer.getRange(0, buffer.length));
     } else {
       _bufferList.add(buffer);
@@ skipping 65 matching lines @@
   }
 
   _BufferList _bufferList;
   bool _streamMarkedClosed = false;
   bool _closeCallbackCalled = false;
   Timer _scheduledNoPendingWriteCallback;
   Timer _scheduledCloseCallback;
   Function _clientNoPendingWriteHandler;
   Function _clientCloseHandler;
 }