Add support for TokenStream, LocalVarDescriptors, and PcDescriptors to service lib and generic obje…

runtime/bin/vmservice/observatory/lib/src/elements/context_ref.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 context_ref_element;
 
 import 'package:polymer/polymer.dart';
 import 'package:observatory/service.dart';
 import 'service_ref.dart';
 
 @CustomTag('context-ref')
 class ContextRefElement extends ServiceRefElement {
   ContextRefElement.created() : super.created();
 
   // TODO(turnidge): This is here to workaround vm/dart2js differences.
   dynamic expander() {
     return expandEvent;
   }
 
   void expandEvent(bool expand, Function onDone) {
     assert(ref is Context);
     if (expand) {
       ref.reload().then((result) {
         ref = result;
         notifyPropertyChange(#ref, 0, 1);
       }).whenComplete(onDone);
     } else {
       Context refMap = ref;
-      refMap.elements = null;
+      refMap.variables = null;
       onDone();
     }
   }
 }