anchor.diff:  /**
    * Implements the dart:html Shelf adapter.
    */
  -Future<Local> serve(handler, [Window window]) {
  -  return new Future.value(new Local(handler, window));
  +Future<Local> serve(handler) {
  +  return new Future.value(new Local(handler));
   }
positive.code: class Local { // TODO: find a better name.
    dynamic _handler;
  
    // The window is injected to make the class testable through mocks.
    Window _window;
  
    Local(this._handler, [this._window]) {
      if (_window == null) _window = window;
  
      _window.onPopState.listen(_onWindowLocationChange);
  
      // Handle the initial window location.
      _onWindowLocationChange();
  
negative.code:    * [_onWindowLocationChange] event handler.
     */
    void go(String path, {Map state: const {}, String title: ''}) {
      window.history.pushState(state, title, path);
      _onWindowLocationChange();
    }
  
    void _onWindowLocationChange([PopStateEvent e]) {
      final request = new Request('GET', new Uri(scheme: 'http', path: window.location.pathname));
      _handler(request).then((Response response) {
        switch (response.statusCode) {
          // If the statusCode of the  response is 30x perform an 'internal redirect'
  