Merge pull request #1702 from pandamicro/develop-3.0

Issue #4294: Fix ccs.comAttribute API incompatible issue
Fixed a bug of Sprite that it doesn't work when its texture doesn't preload and its parent is a SpriteBatchNode
Merge branch 'develop-3.0' of git://github.com/cocos2d/cocos2d-html5 into Iss3767_DrawNode
Merge pull request #1704 from dingpinglv/Iss3767_DrawNode

Fixed a bug of Sprite that it doesn't work when its texture doesn't preload and its parent is a SpriteBatchNode
Fixed #192: fixed a bug in CCBoot.js that it has a error on Firefox.
Merge branch 'develop-3.0' of git://github.com/cocos2d/cocos2d-html5 into Iss3767_DrawNode
Merge pull request #1705 from dingpinglv/Iss3767_DrawNode

Fixed #192: fixed a bug in CCBoot.js that it has a error on Firefox.
Fixed #4456: Use undefined check in cc.loader and fix comment errors