Add Zone support for Timers.

sdk/lib/async/future_impl.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;
 
 deprecatedFutureValue(_FutureImpl future) =>
   future._isComplete ? future._resultOrListeners : null;
 
 abstract class _Completer<T> implements Completer<T> {
@@ skipping 120 matching lines @@
   _FutureListener _nextListener;
   final _FutureListener _listener;
 
   _ErrorZoneBoundaryListener(this._listener);
 
   bool _inSameErrorZone(_Zone otherZone) {
     // Should never be called. We use [_inSameErrorZone] to know if we have
     // to insert an instance of [_ErrorZoneBoundaryListener] (and in the
     // controller). Once we have inserted one we should never need to use it
     // anymore.
-    // It would be valid to `return true` instead.
     throw new UnsupportedError(
         "A Zone boundary doesn't support the inSameErrorZone test.");
   }
 
   void _sendValue(value) {
     _listener._sendValue(value);
   }
 
   void _sendError(error) {
     // We are not allowed to send an error from one error-zone to another.
@@ skipping 502 matching lines @@
           _setError(error);
         }, onError: _setError);
         return;
       }
     } catch (e, s) {
       error = _asyncError(e, s);
     }
     _setError(error);
   }
 }