anchor.diff:  
     VMService._(this._connection);
   
  -  Future<VM> getVM() =>
  -      _connection.request('getVM').then((resp) => new VM.fromJson(resp));
  -
  -  Future<Isolate> getIsolate(String isolateId) {
  -    return _connection
  -        .request('getIsolate', {'isolateId': isolateId})
  -        .then((resp) => new Isolate.fromJson(resp));
  +  Future<VM> getVM() async {
  +    var response = await _connection.request('getVM');
  +    return new VM.fromJson(response);
  +  }
  +
  +  Future<Isolate> getIsolate(String isolateId) async {
  +    var response =
  +        await _connection.request('getIsolate', {'isolateId': isolateId});
  +    return new Isolate.fromJson(response);
     }
   
     Future<AllocationProfile> getAllocationProfile(String isolateId,
  -      {bool reset, bool gc}) {
  +      {bool reset, bool gc}) async {
       var params = {'isolateId': isolateId};
       if (reset != null) {
         params['reset'] = reset;
  
positive.code:       return debuggerUrl;
      }
  
      return http.get(uri).then((response) {
        var webSocketDebuggerUrl = _getWebsocketDebuggerUrl(response);
        return WebSocket
            .connect(webSocketDebuggerUrl)
            .then((socket) => new _DevtoolsConnection(socket));
      });
    }
  
    Future<Map> request(String request, [Map params = const {}]) {
  
negative.code:     _socket.listen(_handleResponse);
    }
  
    static Future<_Connection> connect(String host, int port) async {
      _log.fine('Connecting to VM via HTTP websocket protocol');
      var uri = 'ws://$host:$port/ws';
      var socket = await WebSocket.connect(uri);
      return new _VMWebsocketConnection(socket);
    }
  
    Future<Map> request(String method, [Map params = const {}]) {
  