anchor.diff:  
   /// Creates ReactJS [Component2] instances for Dart components.
   class ReactDartComponentFactoryProxy2<TComponent extends Component2> extends ReactComponentFactoryProxy
  +    with JsBackedMapComponentFactoryMixin
       implements ReactDartComponentFactoryProxy {
     /// The ReactJS class used as the type for all [ReactElement]s built by
     /// this factory.
  
positive.code: 
    @override
    ReactElement build(Map props, [List childrenArgs = const []]) {
      var children = _convertArgsToChildren(childrenArgs);
      children = listifyChildren(children);
  
      // We can't mutate the original since we can't be certain that the value of the
      // the converted event handler will be compatible with the Map's type parameters.
      var convertibleProps = new Map.from(props);
      convertProps(convertibleProps);
  
      // jsifyAndAllowInterop also handles converting props with nested Map/List structures, like `style`
      return factory(jsifyAndAllowInterop(convertibleProps), children);
    }
  
    /// Performs special handling of certain props for consumption by ReactJS DOM components.
  
negative.code:         this.defaultProps = new JsBackedMap.fromJs(reactClass.defaultProps);
  
    ReactClass get type => reactClass;
  }
  
  /// Converts a list of variadic children arguments to children that should be passed to ReactJS.
  