anchor.diff:    }
   
     // TODO(fishythefish): Support required named parameters.
  -  var returnType = Rti._getReturnType(functionType);
  -  var parameters = Rti._getFunctionParameters(functionType);
  +  Rti returnType = Rti._getReturnType(functionType);
  +  _FunctionParameters parameters = Rti._getFunctionParameters(functionType);
     var requiredPositional =
         _FunctionParameters._getRequiredPositional(parameters);
     int requiredPositionalLength = _Utils.arrayLength(requiredPositional);
  
positive.code: 
    static Rti _createFunctionRti(Object universe, Rti returnType,
        _FunctionParameters parameters, String canonicalRecipe) {
      var rti = Rti.allocate();
      Rti._setKind(rti, Rti.kindFunction);
      Rti._setPrimary(rti, returnType);
      Rti._setRest(rti, parameters);
  
negative.code:             break;
  
            case Recipe.wrapFutureOr:
              Object u = universe(parser);
              push(
                  stack,
                  _Universe._lookupFutureOrRti(
  