anchor.diff:  
   final bool _isInCheckedMode = _initIsInCheckedMode();
   final bool _shouldLogRenderDuration = false;
  +final bool _shouldTrace = false;
   
   class Style {
     final String _className;
  
positive.code:       return;
  
      assert(_host != null);
      _sync(null, _host, _insertionPoint);
    }
  
  
negative.code:     currentNode = null;
      while (oldStartIndex < oldEndIndex) {
        oldNode = oldChildren[oldStartIndex];
        _removeChild(oldNode);
        advanceOldStartIndex();
      }
    }
  