anchor.diff:      assert(!_needsPaint);
     }
   
  -  bool get createNewDisplayList => false;
  +  bool get requiresCompositing => false;
     Rect get paintBounds;
     void debugPaint(PaintingContext context, Offset offset) { }
     void paint(PaintingContext context, Offset offset) { }
  
positive.code: 
    static List<RenderObject> _nodesNeedingPaint = new List<RenderObject>();
  
    final sky.PaintingNode _paintingNode = new sky.PaintingNode();
    sky.PaintingNode get paintingNode {
      assert(createNewDisplayList);
      return _paintingNode;
    }
    bool _needsPaint = true;
    bool get needsPaint => _needsPaint;
  
  
negative.code:     }
    }
  
    void _repaint() {
      assert(!_needsLayout);
      assert(requiresCompositing);
      sky.PictureRecorder recorder = new sky.PictureRecorder();
      sky.Canvas canvas = new sky.Canvas(recorder, paintBounds);
      PaintingContext context = new PaintingContext(canvas);
  