Fix typo in fetch.dart

sky/sdk/lib/framework/net/fetch.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import '../shell.dart' as shell;
 import 'dart:async';
 import 'dart:typed_data';
 import 'package:mojo/core.dart' as core;
 import 'package:mojom/mojo/network_service.mojom.dart';
 import 'package:mojom/mojo/url_loader.mojom.dart';
@@ skipping 26 matching lines @@
 
 Future<UrlResponse> fetchUrl(String relativeUrl) async {
   String url = Uri.base.resolve(relativeUrl).toString();
   UrlRequest request = new UrlRequest()
     ..url = url
     ..autoFollowRedirects = true;
   return fetch(request);
 }
 
 Future<Response> fetchBody(String relativeUrl) async {
-  UrlResponse response = await fetchMojo(relativeUrl);
+  UrlResponse response = await fetchUrl(relativeUrl);
   if (response.body == null) return new Response(null);
 
   ByteData data = await core.DataPipeDrainer.drainHandle(response.body);
   return new Response(data);
 }