fixed a bug of cc.ProgressTimer that it has a blink when its reverseDirection equals false and type equals cc.PROGRESS_TIMER_TYPE_RADIAL
Merge pull request #1354 from dingpinglv/Iss_ProgressTimerFixed

fixed a bug of cc.ProgressTimer that it has a blink when its reverseDirection equals false and type equals cc.PROGRESS_TIMER_TYPE_RADIAL