Closed #3568: Fix a bug of LabelAtlas that it doesn't work when contentScaleFactor sets.
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-html5 into Iss3568_FixLabelAtlasBug
Merge pull request #1414 from dingpinglv/Iss3568_FixLabelAtlasBug

Closed #3568: Fixed a bug of LabelAtlas that it doesn't work when contentScaleFactor sets.