Add a ListOutputStream.onData callback.

runtime/bin/list_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.
 
 /**
  * [ListInputStream] makes it possible to use the [InputStream]
  * interface to stream over data that is received in chunks as lists
  * of integers.
  *
  * When a new list of integers is received it can be written to the
@@ skipping 25 matching lines @@
  * [ListOutputStream] makes it possible to use the [OutputStream]
  * interface to write data to a [List] of integers.
  */
 interface ListOutputStream extends OutputStream default _ListOutputStream {
   /**
    * Create a [ListOutputStream].
    */
   ListOutputStream();
 
   /**
-   * Get the contents written to the [ListOutputStream].
+   * Reads all available data from the stream. If no data is available `null`
+   * will be returned.
    */
-  List<int> contents();
+  List<int> read();
+
+  /**
+   * Sets the handler that gets called when data is available.
+   */
+  void set onData(void callback());
 }