anchor.diff:          type = PixelType.unsignedByte;
   
     Uint8List getPixelData() => data;
  +
  +  Future<Uint8ListImage> asFuture() => new Future.value(this);
   }
   
   class Uint8ClampedListImage implements TextureImage {
  
positive.code:   int get height;
  
    bool get isReady;
  }
  
  class Texture2D implements Texture {
  
negative.code: 
      return _data;
    }
  
    Future<ImageDataImage> asFuture() => new Future.value(this);
  }
  
  class ImageElementImage implements TextureImage {
  