fixed #2144 fixed a bug of cc.ParticleSystem that the _totalParticles is wrong on canvas mode.
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-html5 into Iss2144_FixBugForParticleSystem
Merge pull request #967 from dingpinglv/Iss2144_FixBugForParticleSystem

fixed #2144 fixed a bug of cc.ParticleSystem that the _totalParticles is wrong on canvas mode.