anchor.diff:  
     @override
     void addToScene(ui.SceneBuilder builder, Offset layerOffset) {
  -    Timeline.startSync('ChildSceneLayer::addToScene');
       builder.addChildScene(
         offset + layerOffset,
         devicePixelRatio,
  
positive.code: 
    @override
    void addToScene(ui.SceneBuilder builder, Offset layerOffset) {
      Timeline.startSync('OffsetLayer::addToScene');
      addChildrenToScene(builder, offset + layerOffset);
      Timeline.finishSync();
    }
  
    @override
  
negative.code: 
    @override
    void addToScene(ui.SceneBuilder builder, Offset layerOffset) {
      Matrix4 effectiveTransform = new Matrix4.translationValues(offset.dx + layerOffset.dx, offset.dy + layerOffset.dy, 0.0)
        ..multiply(transform);
      builder.pushTransform(effectiveTransform.storage);
      addChildrenToScene(builder, Offset.zero);
      builder.pop();
    }
  
    @override
  