Add breadcrumb for the VM.

runtime/observatory/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:async';
 import 'dart:html';
 import 'observatory_element.dart';
 import 'package:observatory/service.dart';
@@ skipping 48 matching lines @@
   }
 }
 
 @CustomTag('top-nav-menu')
 class TopNavMenuElement extends ObservatoryElement {
   @published bool last = false;
 
   TopNavMenuElement.created() : super.created();
 }
 
+@CustomTag('vm-nav-menu')
+class VMNavMenuElement extends ObservatoryElement {
+  @published bool last = false;
+  @published VM vm;
+
+  VMNavMenuElement.created() : super.created();
+}
+
 @CustomTag('isolate-nav-menu')
 class IsolateNavMenuElement extends ObservatoryElement {
   @published bool last = false;
   @published Isolate isolate;
 
   IsolateNavMenuElement.created() : super.created();
 }
 
 @CustomTag('library-nav-menu')
 class LibraryNavMenuElement extends ObservatoryElement {
@@ skipping 39 matching lines @@
     app.removePauseEvents(event.isolate);
     return event.isolate.stepOut();
   }
 
   void closeItem(MouseEvent e, var detail, Element target) {
     events.remove(event);
   }
 
   NavNotifyItemElement.created() : super.created();
 }