Join Our Free Newsletter * Dow, S&P 500 closed at all-time highs Monday * Market closes early, remains shut through Christmas Day * Dow up 0.2 pct, S&P 500 up 0.1 pct, Nasdaq flat By Ryan Vlastelica NEW YORK, Dec 24 (Reuters) – U.S. stocks were little changed on Tuesday as investors refrained from making big bets ahead of the Christmas…