anchor.diff:    }
   
     void _remove() {
  -    content._remove();
  +    _removeChild(content);
       super._remove();
     }
   }
  
positive.code:   Node _parent;
    sky.Node _root;
    bool _defunct = false;
  
    Node({ Object key }) {
      _key = key == null ? "$runtimeType" : "$runtimeType-$key";
  
negative.code:     super._remove();
      if (_children != null) {
        for (var child in _children) {
          _removeChild(child);
        }
      }
    }
  