cocos2d/cocos2d-x — pull request #7782 by liang8305 (2014-08-14 09:07:33+00:00)
Title: mLastTickInNanoSeconds is the renderStart

because:
this.mLastTickInNanoSeconds = renderEnd - renderInterval;
renderInterval = renderEnd - renderStart
so:
this.mLastTickInNanoSeconds = renderEnd - ( renderEnd - renderStart );
so:
this.mLastTickInNanoSeconds = renderStart ;

so:
no need nanoTime() twice