anchor.diff:    }
   }
   
  -class Node {
  +class Node extends EventTarget {
     Stream<KeyEvent> get onKeyDown => new _EventStream(this, 'keydown');
     Stream<KeyEvent> get onKeyUp => new _EventStream(this, 'keyup');
     Stream<MouseEvent> get onMouseDown => new _EventStream(this, 'mousedown');
  
positive.code:   set height(int heightp) => _height = heightp;
  
    ImageElement({String srcp, int widthp, int heightp})
      : on = new ElementEvents(),
        _src = srcp,
        _width = widthp,
        _height = heightp {
    }
  
negative.code: void C2DCreateNativeContext(int handle, int width, int height)
      native "C2DCreateNativeContext";
  
  class ImageElement extends Node {
    Stream<Event> get onLoad => new _EventStream(this, 'load');
  
    String _src;
    int _width;
    int _height;
  