Merge pull request #1160 from dingpinglv/Iss2833_ReturnNewObjectForFunciton

fixed #2833: correct a mistake for latest commit
Fixed #2833: refactor cc.Sprite's _rect to make its fault tolerance stronger
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-html5 into Iss2833_ReturnNewObjectForFunciton