Make Stream.where, etc., be documented as inheriting broadcast state.

sdk/lib/async/stream_transformers.dart

 // Copyright (c) 2013, 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;
 
 /**
  * Wraps an [_EventSink] so it exposes only the [EventSink] interface.
  */
 class _EventSinkWrapper<T> implements EventSink<T> {
@@ skipping 153 matching lines @@
  * The result of binding a StreamTransformer for Sink-mappers.
  *
  * It contains the bound Stream and the sink-mapper. Only when the user starts
  * listening to this stream is the sink-mapper invoked. The result is used
  * to create a StreamSubscription that transforms events.
  */
 class _BoundSinkStream<S, T> extends Stream<T> {
   final _SinkMapper<S, T> _sinkMapper;
   final Stream<S> _stream;
 
+  bool get isBroadcast => _stream.isBroadcast;
+
   _BoundSinkStream(this._stream, this._sinkMapper);
 
   StreamSubscription<T> listen(void onData(T event),
                                { Function onError,
                                  void onDone(),
                                  bool cancelOnError }) {
     cancelOnError = identical(true, cancelOnError);
     StreamSubscription<T> subscription = new _SinkTransformerStreamSubscription(
         _stream, _sinkMapper, cancelOnError);
     subscription.onData(onData);
@@ skipping 116 matching lines @@
                                  void onDone(),
                                  bool cancelOnError }) {
     cancelOnError = identical(true, cancelOnError);
     StreamSubscription<T> result = _transformer(_stream, cancelOnError);
     result.onData(onData);
     result.onError(onError);
     result.onDone(onDone);
     return result;
   }
 }