Update VM service to new isolate API

tests/standalone/vmservice/test_helper.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 vmservice_test_helper;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'package:expect/expect.dart';
 
 abstract class VmServiceRequestHelper {
   final Uri uri;
   final HttpClient client;
 
   VmServiceRequestHelper(String url) :
       uri = Uri.parse(url),
       client = new HttpClient();
 
   Future makeRequest() {
+    print('** GET: $uri');
     return client.getUrl(uri)
       .then((HttpClientRequest request) => request.close())
       .then((HttpClientResponse response) {
         return response
             .fold(new BytesBuilder(), (b, d) => b..add(d))
             .then((builder) {
-              print('** GET: $uri');
               return _requestCompleted(builder.takeBytes(), response);
             });
       }).catchError((error) {
         onRequestFailed(error);
       });
   }
 
   Future _requestCompleted(List<int> data, HttpClientResponse response) {
     Expect.equals(200, response.statusCode, 'Invalid HTTP Status Code');
     var replyAsString;
@@ skipping 209 matching lines @@
       });
     });
     return Future.wait(requests).then((a) {
       a.forEach((FieldRequestHelper field) {
         fields[field.field['user_name']] = field.field;
       });
       return this;
     });
   }
 }