Issue #5968: fixed a bug of cc.DrawNode and eventHelper
Merge branch 'Renderer' of https://github.com/cocos2d/cocos2d-html5 into Iss5968_RefactorCanvasRenderer
Merge pull request #2357 from dingpinglv/Iss5968_RefactorCanvasRenderer

Issue #5968: fixed bugs of cc.DrawNode and eventHelper