Make Streams also cosider a thrown AsyncError a rethrow.

sdk/lib/async/stream_controller.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.
 
 part of dart.async;
 
 // -------------------------------------------------------------------
 // Default implementation of a stream with a controller for adding
 // events to the stream.
 // -------------------------------------------------------------------
@@ skipping 112 matching lines @@
    * Called when the first listener subscribes or the last unsubscribes.
    *
    * Read [hasSubscribers] to see what the new state is.
    */
   void onSubscriptionStateChange() {}
 
   void forEachSubscriber(void action(_StreamSubscriptionImpl<T> subscription)) {
     _stream._forEachSubscriber(() {
       try {
         action();
+      } on AsyncError catch (e) {
+        e.throwDelayed();
       } catch (e, s) {
         new AsyncError(e, s).throwDelayed();
       }
     });
   }
 }
 
 typedef void _NotificationHandler();
 
 class _MultiControllerStream<T> extends _MultiStreamImpl<T> {
@@ skipping 18 matching lines @@
   _SingleControllerStream(this._subscriptionHandler, this._pauseHandler);
 
   void _onSubscriptionStateChange() {
     _subscriptionHandler();
   }
 
   void _onPauseStateChange() {
     _pauseHandler();
   }
 }