anchor.diff:      }
       _root = _rendered._root;
       assert(_rendered._root is sky.Node);
  +
  +    if (mounting) {
  +      didMount();
  +    }
     }
   
     void _renderIfDirty() {
  
positive.code:         _order = _currentOrder + 1,
          super(key:key);
  
    void didUnmount() {}
  
    void _remove() {
  
negative.code:     }
  
      var oldRendered = _rendered;
      bool mounting = oldRendered == null;
      int lastOrder = _currentOrder;
      _currentOrder = _order;
      _currentlyRendering = this;
  