anchor.diff:        }
         return this._routerCanDeactivate(instruction).then((bool result) {
           if (result) {
  -          return this.commit(instruction, _skipLocationChange).then((_) {
  +          return this
  +              .commit(instruction, _skipLocationChange, _replaceState)
  +              .then((_) {
               this._emitNavigationFinish(instruction.rootUrl);
               return true;
             });
  
positive.code:   }
  
    /** @internal */
    Future<dynamic> _navigate(Instruction instruction, bool _skipLocationChange) {
      return this
          ._settleInstruction(instruction)
          .then((_) => this._routerCanReuse(instruction))
  
negative.code:     this.parent = parent;
    }
    Future<dynamic> navigateByUrl(String url,
        [bool _skipLocationChange = false, bool _replaceState = false]) {
      // Delegate navigation to the root router
      return this.parent.navigateByUrl(url, _skipLocationChange, _replaceState);
    }
  
    Future<dynamic> navigateByInstruction(Instruction instruction,
        [bool _skipLocationChange = false, bool _replaceState = false]) {
      // Delegate navigation to the root router
      return this
          .parent
          .navigateByInstruction(instruction, _skipLocationChange, _replaceState);
    }
  }
  
  