anchor.diff:  
   // TODO(aa) make FunctionProxy implements Function once it is allowed
   /// A [Proxy] subtype to JavaScript functions.
  -class FunctionProxy extends Proxy implements Serializable<FunctionProxy> /*,Function*/ {
  +class FunctionProxy extends Proxy
  +    implements Serializable<FunctionProxy> /*,Function*/ {
     FunctionProxy._internal(SendPortSync port, id) : super._internal(port, id);
   
     // TODO(vsm): This allows calls with a limited number of arguments
  
positive.code:    * explicitly disposed to avoid memory leaks.
     */
    Callback.many(Function f, {bool withThis: false}) {
      _callback = (List args) => Function.apply(f, withThis ? args : args.skip(1).toList());
      _initialize(true);
    }
  }
  
negative.code: /**
   * Check if [proxy] is instance of [type].
   */
  bool instanceof(Serializable<Proxy> proxy, Serializable<FunctionProxy> type) =>
      _jsPortInstanceof.callSync([proxy.toJs(), type.toJs()].map(_serialize)
          .toList());
  
  
  /**
   * Delete the [name] property of [proxy].
   */
  void deleteProperty(Serializable<Proxy> proxy, String name) {
    _jsPortDeleteProperty.callSync([proxy.toJs(), name].map(_serialize).toList());
  }
  
  /**
  