debugSubtreeNeedsAddToScene property

bool debugSubtreeNeedsAddToScene
@visibleForTesting

Whether any layer in the subtree needs addToScene.

This is for debug and test purpose only. It only becomes valid after calling updateSubtreeNeedsAddToScene.

Implementation 

@visibleForTesting
bool get debugSubtreeNeedsAddToScene {
  bool result;
  assert((){
    result = _subtreeNeedsAddToScene;
    return true;
  }());
  return result;
}