anchor.diff:    Rectangle<int> dst;
     Vector2 offset;
     Vector2 trimmed;
  -  Sprite(Map<String, dynamic> singleAsset) {
  +  Sprite(_FrameValue singleAsset) {
       final _Asset asset = _Asset(singleAsset);
       src = asset.frame;
       var cx, cy;
  
positive.code:         String assetJson) =>
      Future.value(json.decode(assetJson));
  
  Future<Map<String, dynamic>> _processAssets(String assetJson) =>
      Future.value(json.decode(assetJson));
  
negative.code:   bool trimmed;
    Rectangle spriteSourceSize;
    Point sourceSize;
    _Asset(_FrameValue asset)
        : frame = _createRectangle(asset.frame),
          trimmed = asset.trimmed,
          spriteSourceSize = _createRectangle(asset.spriteSourceSize),
          sourceSize = _createPoint(asset.sourceSize);
  }
  
  Rectangle<int> _createRectangle(_SpriteSourceSizeClass rect) =>
      Rectangle(rect.x, rect.y, rect.w, rect.h);
  
  Point<int> _createPoint(_Size size) => Point(size.w, size.h);
  
  Future<Map<String, String>> _processAchievementAssets(String assetJson) =>
      Future.value(json.decode(assetJson));
  