Improve docs
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-js into develop
Fixed #5891: add cc.Layer's bake/unbake/isBaked function in JSB
Remove useless constant
Fixed #5882: Move EventAssetsManager/EventListenerAssetsManager to jsb namespace
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-js into develop
Issue #5892: Fix an issue of AssetsManagerTest
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-js into develop
Issue #5892: Polish AssetsManager
Update html5 engine
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-js into develop
Merge pull request #761 from pandamicro/develop

Issue #5892: Polish AssetsManager