Bay seniors with glittering memories of the Christmas tree under the glass dome in the old Emporium department store, might want to brave the holiday crowds to see how the celebration has been updated. Starting at 5pm every half hour every night from now until December 31 on the 4th floor of the Westfield Mall there is a 3-D Nutcracker film and light show under the restored dome featuring the stars and the corps of SF Ballet’s dazzling production. And this Saturday from 5-6 you can meet the actual dancers themselves. All for free. Nice.