Move image loading out of C++ into Dart

sky/examples/stocks/lib/stock_data.dart

 // Copyright 2014 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 'dart:convert';
 import 'dart:math';
 import 'package:sky/framework/net/fetch.dart';
 
 // Snapshot from http://www.nasdaq.com/screening/company-list.aspx
 // Fetched 2/23/2014.
@@ skipping 41 matching lines @@
 
 class StockDataFetcher {
   int _currentChunk = 0;
   final StockDataCallback callback;
 
   StockDataFetcher(this.callback) {
     _fetchNextChunk();
   }
 
   void _fetchNextChunk() {
-    fetch('data/stock_data_${_currentChunk++}.json').then((Response response) {
+    fetchBody('data/stock_data_${_currentChunk++}.json').then((Response response) {
       String json = response.bodyAsString();
       JsonDecoder decoder = new JsonDecoder();
 
       callback(new StockData(decoder.convert(json)));
 
       if (_currentChunk < _kChunkCount)
         _fetchNextChunk();
     });
   }
 }