anchor.diff:      currentNode = null;
       while (oldStartIndex < oldEndIndex) {
         oldNode = oldChildren[oldStartIndex];
  -      oldNode._remove();
  +      _removeChild(oldNode);
         advanceOldStartIndex();
       }
     }
  
positive.code:       return;
  
      assert(_host != null);
      _sync(null, _host, _insertionPoint);
    }
  
  
negative.code:   }
  
    void _remove() {
      _removeChild(content);
      super._remove();
    }
  }
  