Add support for asynchronous event notification to the observatory.

runtime/bin/vmservice/client/lib/src/elements/nav_bar.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 nav_bar_element;
 
 import 'dart:html';
 import 'observatory_element.dart';
 import 'package:observatory/app.dart';
 import 'package:observatory/service.dart';
@@ skipping 98 matching lines @@
   LibraryNavMenuElement.created() : super.created();
 }
 
 @CustomTag('class-nav-menu')
 class ClassNavMenuElement extends ObservatoryElement {
   @published Class cls;
   @published bool last = false;
 
   ClassNavMenuElement.created() : super.created();
 }
+
+@CustomTag('nav-notify')
+class NavNotifyElement extends ObservatoryElement {
+  @published ObservableList<ServiceEvent> events;
+  
+  NavNotifyElement.created() : super.created();
+}
+
+@CustomTag('nav-notify-item')
+class NavNotifyItemElement extends ObservatoryElement {
+  @published ObservableList<ServiceEvent> events;
+  @published ServiceEvent event;
+  
+  void closeItem(MouseEvent e, var detail, Element target) {
+    events.remove(event);
+  }
+
+  NavNotifyItemElement.created() : super.created();
+}