anchor.diff:  import 'shell.dart';
   
   abstract class AssetBundle {
  -  void close();
     ImageResource loadImage(String key);
     Future<String> loadString(String key);
     Future<core.MojoDataPipeConsumer> load(String key);
  
positive.code:   NetworkAssetBundle(Uri baseUrl) : _baseUrl = baseUrl;
  
    final Uri _baseUrl;
  
    void close() { }
  
    String _urlFromKey(String key) => _baseUrl.resolve(key).toString();
  
  
negative.code:   AssetBundleProxy _bundle;
    Map<String, ImageResource> _imageCache = new Map<String, ImageResource>();
    Map<String, Future<String>> _stringCache = new Map<String, Future<String>>();
  
    Future<ui.Image> _fetchImage(String key) async {
      return await decodeImageFromDataPipe(await load(key));
  