Block shine animation

[cxong]

In many match 3 games, there will be some sort of block animation; for example, see Bejeweled: http://youtu.be/BnljGFVDAuo?t=23s Panel de pon: http://youtu.be/s5diMK79kPE?t=3m37s

Here I've mocked up some simple shining animations for the blocks:

http://jsfiddle.net/60wuv5wo/