anchor.diff:      super.mount(parent, slot);
     }
   
  +  void _notifyChildren(Element child) {
  +    if (child is RenderObjectElement) {
  +      child._updateParentData(widget);
  +    } else {
  +      assert(child is! ParentDataElement<RenderObjectWidget>);
  +      child.visitChildren(_notifyChildren);
  +    }
  +  }
  +
     @override
     void notifyClients(ParentDataWidget<T> oldWidget) {
  -    void notifyChildren(Element child) {
  -      if (child is RenderObjectElement) {
  -        child._updateParentData(widget);
  -      } else {
  -        assert(child is! ParentDataElement<RenderObjectWidget>);
  -        child.visitChildren(notifyChildren);
  -      }
  -    }
  -    visitChildren(notifyChildren);
  -  }
  -}
  -
  -/// Base class for instantiations of [InheritedWidget] subclasses.
  +    visitChildren(_notifyChildren);
  +  }
  +}
  +
  +/// An element that uses a [InheritedWidget] as its configuration.
   class InheritedElement extends ProxyElement {
  +  /// Creates an element that uses the given widget as its configuration.
     InheritedElement(InheritedWidget widget) : super(widget);
   
     @override
  
positive.code: ///  * At this point, the element is considered "defunct" and will not be
  ///    incorporated into the tree in the future.
  abstract class Element implements BuildContext {
    /// Creates an element that instantiates the given widget.
    ///
    /// Typically called by an override of [Widget.createElement].
    Element(Widget widget) : _widget = widget {
  
negative.code:   }
  }
  
  /// An element that uses a [SingleChildRenderObjectWidget] as its configuration.
  ///
  /// The child is optional.
  ///
  