anchor.diff:      ui.Offset offset = ui.Offset.zero,
       ui.OpacityEngineLayer? oldLayer,
     }) {
  -    return _pushSurface(PersistedOpacity(oldLayer as PersistedOpacity?, alpha, offset)) as ui.OpacityEngineLayer;
  +    return _pushSurface<PersistedOpacity>(PersistedOpacity(oldLayer as PersistedOpacity?, alpha, offset));
     }
   
     /// Pushes a color filter operation onto the operation stack.
  
positive.code:     ui.ColorFilterEngineLayer? oldLayer,
    }) {
      assert(filter != null); // ignore: unnecessary_null_comparison
      return _pushSurface(PersistedColorFilter(oldLayer as PersistedColorFilter?, filter)) as ui.ColorFilterEngineLayer;
    }
  
    /// Pushes an image filter operation onto the operation stack.
  
negative.code:     ui.PhysicalShapeEngineLayer? oldLayer,
    }) {
      assert(color != null, 'color must not be null'); // ignore: unnecessary_null_comparison
      return _pushSurface<PersistedPhysicalShape>(PersistedPhysicalShape(
        oldLayer as PersistedPhysicalShape?,
        path as SurfacePath,
        elevation,
        color.value,
        shadowColor?.value ?? 0xFF000000,
        clipBehavior,
      ));
    }
  
    /// Add a retained engine layer subtree from previous frames.
  