anchor.diff:  
     @override
     void addToScene(ui.SceneBuilder builder, Offset layerOffset) {
  -    addChildrenToScene(builder, layerOffset);
  +    Timeline.startSync('ContainerLayer::addToScene');
  +    addChildrenToScene(builder, layerOffset);
  +    Timeline.finishSync();
     }
   
     /// Uploads all of this layer's children to the engine
  
positive.code: 
    @override
    void addToScene(ui.SceneBuilder builder, Offset layerOffset) {
      builder.pushClipRect(clipRect.shift(layerOffset));
      addChildrenToScene(builder, layerOffset);
      builder.pop();
    }
  
    @override
  
negative.code: 
    @override
    void addToScene(ui.SceneBuilder builder, Offset layerOffset) {
      Timeline.startSync('OffsetLayer::addToScene');
      addChildrenToScene(builder, offset + layerOffset);
      Timeline.finishSync();
    }
  
    @override
  