anchor.diff:      Token period = null;
       SimpleIdentifier constructorName = null;
       if (_matches(TokenType.PERIOD)) {
  -      period = andAdvance;
  +      period = getAndAdvance();
         constructorName = parseSimpleIdentifier();
       }
       ArgumentList argumentList = parseArgumentList();
  
positive.code:               [_currentToken.lexeme]);
            _advance();
          } else {
            modifiers.externalKeyword = andAdvance;
          }
        } else if (_matchesKeyword(Keyword.FACTORY) &&
            !_tokenMatches(_peek(), TokenType.PERIOD) &&
  
negative.code:     Expression expression;
      if (_matchesKeyword(Keyword.SUPER) &&
          _currentToken.next.type.isMultiplicativeOperator) {
        expression = new SuperExpression(getAndAdvance());
      } else {
        expression = _parseUnaryExpression();
      }
      while (_currentToken.type.isMultiplicativeOperator) {
        Token operator = getAndAdvance();
        expression =
            new BinaryExpression(expression, operator, _parseUnaryExpression());
      }
  