Rename unsubscribe to cancel.

sdk/lib/async/stream_pipe.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;
 
 /**
  * A pipe between two streams.
  *
  * The default pipe subscribes to the [source] and sends on the
@@ skipping 38 matching lines @@
     * [stream] has subscribers.
     */
   void _onSubscriptionStateChange() {
     if (_hasSubscribers) {
       assert(_subscription == null);
       if (_source != null) {
         _subscribeToSource();
       }
     } else {
       if (_subscription != null) {
-        _subscription.unsubscribe();
+        _subscription.cancel();
         _subscription = null;
       }
     }
   }
 
   void _onPauseStateChange() {
     if (_subscription == null) return;
     if (isPaused) {
       _subscription.pause();
     } else {
@@ skipping 381 matching lines @@
         _signalError(new AsyncError(e, s));
         return null;
       }
       if (!isEqual) {
         _add(inputEvent);
         _previous = inputEvent;
       }
     }
   }
 }