anchor.diff:        _renderObject = createNode();
         assert(_renderObject != null);
         _ancestor = findAncestorRenderObjectWrapper();
  -      if (_ancestor is RenderObjectWrapper)
  +      if (_ancestor != null)
           _ancestor.insertChildRenderObject(this, slot);
       } else {
         _renderObject = old.renderObject;
  
positive.code:     newNode._ancestor = _ancestor;
    }
  
    void _sync(RenderObjectWrapper old, dynamic slot) {
      // TODO(abarth): We should split RenderObjectWrapper into two pieces so that
      //               RenderViewObject doesn't need to inherit all this code it
  
negative.code:   // 'slot' is the identifier that the ancestor RenderObjectWrapper uses to know
    // where to put this descendant. If you just defer to a child, then make sure
    // to pass them the slot.
  
    Set<Type> _dependencies;
    Inherited inheritedOfType(Type targetType) {
  