fixed #208: fixed a TMXLayer's bug
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-html5 into Iss208_FixATileMapBug
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-html5 into Iss208_FixATileMapBug
Merge pull request #1129 from dingpinglv/Iss208_FixATileMapBug

fixed #208: fixed a TMXLayer's bug