Add support for asynchronous event notification to the observatory.

runtime/bin/vmservice/client/lib/src/elements/observatory_element.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.
 
 library observatory_element;
 
 import 'dart:html';
 import 'package:observatory/app.dart';
 import 'package:polymer/polymer.dart';
 
 /// Base class for all Observatory custom elements.
 @CustomTag('observatory-element')
 class ObservatoryElement extends PolymerElement {
   ObservatoryElement.created() : super.created();
 
+  ObservatoryApplication get app => ObservatoryApplication.app;
+
   @override
   void attached() {
     super.attached();
   }
 
   @override
   void attributeChanged(String name, var oldValue, var newValue) {
     super.attributeChanged(name, oldValue, newValue);
   }
 
@@ skipping 78 matching lines @@
               'Bool',
               'String',
               'Double',
               'Instance',
               'GrowableObjectArray',
               'Array',
               'Type',
               'Error'].contains(type));
   }
 }