anchor.diff:          type = PixelType.unsignedShort_5_5_5_1;
   
     Uint16List getPixelData() => data;
  +
  +  Future<Uint16ListImage> asFuture() => new Future.value(this);
   }
   
   enum PixelFormat { RGB, RGBA, luminance, luminanceAlpha, alpha, _depth }
  
positive.code:       : image = image,
          internalFormat = image.format;
  
    factory Texture2D.fromURL(String url, {internalFormat: PixelFormat.RGBA}) =>
        new Texture2D.fromImageElement(new ImageElement(src: url),
            internalFormat: internalFormat);
  
    Texture2D.fromImageData(ImageData imageData,
  
negative.code: 
      return _data;
    }
  
    Future<ImageDataImage> asFuture() =>
        imageElement.onLoad.first.then((i) => this);
  }
  
  class CanvasElementImage implements TextureImage {
  