Add Stream.empty.

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;
 
 // -------------------------------------------------------------------
 // Controller for creating and adding events to a stream.
 // -------------------------------------------------------------------
 
@@ skipping 158 matching lines @@
    */
   bool get isPaused;
 
   /** Whether there is a subscriber on the [Stream]. */
   bool get hasListener;
 
   /**
    * Send or enqueue an error event.
    *
    * If [error] is `null`, it is replaced by a [NullThrownError].
-   *
-   * Also allows an objection stack trace object, on top of what [EventSink]
-   * allows.
    */
   void addError(Object error, [StackTrace stackTrace]);
 
   /**
    * Receives events from [source] and puts them into this controller's stream.
    *
    * Returns a future which completes when the source stream is done.
    *
    * Events must not be added directly to this controller using [add],
    * [addError], [close] or [addStream], until the returned future
@@ skipping 710 matching lines @@
   _StreamControllerAddStreamState(_StreamController controller,
                                   this.varData,
                                   Stream source,
                                   bool cancelOnError)
       : super(controller, source, cancelOnError) {
     if (controller.isPaused) {
       addSubscription.pause();
     }
   }
 }