anchor.diff:                    ARROBA, NAME, null, LPAREN, current, arg, null);
               } else {
                 errors.add(
  -                  new SyntaxError('Missing \')\'', arg.valueOrVariable.span));
  +                  new SyntaxError('Missing \')\'', arg.value.span));
                 return null;
               }
             } else {
  
positive.code: 
        if (next(TokenType.COLON)) {
          var COLON = current;
          var value = parseValue();
  
          if (value != null) {
            return new ObjectFieldContext(NAME, COLON, value);
  
negative.code:       var NAME = current;
        if (next(TokenType.COLON)) {
          var COLON = current;
          var val = parseInputValue();
          if (val != null)
            return new ArgumentContext(NAME, COLON, val);
          else {
  