cocos2d/cocos2d-x — pull request #5120 by ricardoquesada (2014-01-18 07:11:13+00:00)
Title: Renderer: Don't sort z=0 Commands

If Command has z==0, then those elements won't be sorted.
Only Z !=0 will be sorted, and it will use `sort` instead of `stable_sort`
for z!=0, since it is faster