修复BrowserTypes正则表达式匹配失败时的报错

修复BrowserTypes正则表达式匹配失败时的报错
Merge pull request #1097 from WanderWang/develop

fix crash when BrowserTypes match nothing from navigator.userAgent .
Merge branch 'develop' of github.com:cocos2d/cocos2d-html5 into develop