anchor.diff:  }
   
   /// Base class for instantiations of [InheritedWidget] subclasses.
  -class InheritedElement extends _ProxyElement {
  +class InheritedElement extends ProxyElement {
     InheritedElement(InheritedWidget widget) : super(widget);
   
     @override
  
positive.code: /// A [ParentDataWidget] is specific to a particular kind of [RenderObject], and
  /// thus also to a particular [RenderObjectWidget] class. That class is `T`, the
  /// [ParentDataWidget] type argument.
  abstract class ParentDataWidget<T extends RenderObjectWidget> extends _ProxyWidget {
    const ParentDataWidget({ Key key, Widget child })
      : super(key: key, child: child);
  
  
negative.code:   }
  
    @override
    void update(ProxyWidget newWidget) {
      ProxyWidget oldWidget = widget;
      assert(widget != null);
      assert(widget != newWidget);
      super.update(newWidget);
  