fixed #2852: Correct RenderTexture's mistake for multiple resolution resources.
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-html5 into Iss2852_RefactorMultResources
Merge pull request #1183 from dingpinglv/Iss2852_RefactorMultResources

fixed #2852: Correct RenderTexture's mistake for multiple resolution resources.