anchor.diff:      }
     }
   
  -  static void toTypesNamed(Object? universe, Rti environment, Object? items) {
  +  static void toTypesNamed(Object? universe, Rti? environment, Object? items) {
       int length = _Utils.arrayLength(items);
       assert(_Utils.isMultipleOf(length, 3));
       for (int i = 2; i < length; i += 3) {
  
positive.code: 
    // Field accessors for the parser.
    static Object universe(Object? parser) => JS('', '#.u', parser);
    static Rti environment(Object? parser) => JS('Rti', '#.e', parser);
    static String recipe(Object? parser) => JS('String', '#.r', parser);
    static Object stack(Object? parser) => JS('', '#.s', parser);
    static int position(Object? parser) => JS('int', '#.p', parser);
  
negative.code:       push(
            stack,
            _Universe.evalTypeVariable(
                universe(parser), environment(parser)!, string));
      } else {
        push(stack, string);
      }
  