Add pause/resume for isolates in vmservice/observatory.

runtime/bin/vmservice/client/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:html';
 import 'observatory_element.dart';
 import 'package:observatory/app.dart';
 import 'package:observatory/service.dart';
@@ skipping 231 matching lines @@
   }
 
   @observable String formattedTotalCollectionTime(bool newSpace) {
     if (profile == null) {
       return '';
     }
     String space = newSpace ? 'new' : 'old';
     Map heap = profile['heaps'][space];
     return '${Utils.formatSeconds(heap['time'])} secs';
   }
-}
+}