fixed #2293 fixed a bug of cc.LabelTTF when its stroke or shadow enables on Canvas Mode
fixed #2293 fixed a bug of cc.LabelTTF when its stroke or shadow enables on WebGL Mode
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-html5 into Iss2362_AddLogToSchedule
Merge pull request #1031 from dingpinglv/Iss2293_FixLabelTTFBug

Fixed #2293 fixed a bug of cc.LabelTTF that It doesn't work when call enableStroke or enableShadow