Make VM event streams look like real dart streams.

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

 // Copyright (c) 2015, 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 ports;
 
 import 'dart:async';
-import 'dart:html';
 import 'observatory_element.dart';
-import 'package:observatory/app.dart';
 import 'package:observatory/service.dart';
 import 'package:polymer/polymer.dart';
 
 @CustomTag('ports-page')
 class PortsPageElement extends ObservatoryElement {
   PortsPageElement.created() : super.created();
 
   @observable Isolate isolate;
-  @observable /*ObservableList | ServiceObject*/ ports;
+  @observable var /*ObservableList | ServiceObject*/ ports;
 
   void isolateChanged(oldValue) {
     if (isolate != null) {
       isolate.getPorts().then(_refreshView);
     }
   }
 
   Future refresh() {
     return isolate.getPorts().then(_refreshView);
   }
 
   _refreshView(/*ObservableList | ServiceObject*/ object) {
     ports = object['ports'];
   }
 }