Add the streamListen and streamCancel rpcs to the vm service.

runtime/observatory/lib/src/elements/heap_profile.dart

 // Copyright (c) 2014, 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 heap_profile_element;
 
 import 'dart:async';
 import 'dart:html';
 import 'observatory_element.dart';
 import 'package:observatory/app.dart';
@@ skipping 76 matching lines @@
 
   @override
   void attached() {
     super.attached();
     // Grab the pie chart divs.
     _newPieChart = new Chart('PieChart',
         shadowRoot.querySelector('#newPieChart'));
     _oldPieChart = new Chart('PieChart',
         shadowRoot.querySelector('#oldPieChart'));
     _classTableBody = shadowRoot.querySelector('#classTableBody');
-    _subscription = app.vm.events.stream.where(
+    _subscription = app.vm.gcEvents.where(
         (event) => event.isolate == isolate).listen(_onEvent);
   }
 
   @override
   void detached() {
     _subscription.cancel();
     super.detached();
   }
   
   // Keep at most one outstanding auto-refresh RPC.
@@ skipping 253 matching lines @@
   }
 
   @observable String formattedTotalCollectionTime(bool newSpace) {
     if (profile == null) {
       return '';
     }
     var heap = newSpace ? isolate.newSpace : isolate.oldSpace;
     return '${Utils.formatSeconds(heap.totalCollectionTimeInSeconds)} secs';
   }
 }