jQuery浏览器判断一个bug，以及修改建议

var userAgent = navigator.userAgent.toLowerCase();
jQuery.browser = {
	version: (userAgent.match( /.+(?:rv|it|ra|ie)[\/: ]([\d.]+)/ ) || [0,'0'])[1],
	safari: /webkit/.test( userAgent ),
	opera: /opera/.test( userAgent ),
	msie: /msie/.test( userAgent ) && !/opera/.test( userAgent ),
	mozilla: /mozilla/.test( userAgent ) && !/(compatible|webkit)/.test( userAgent )
};

var browserName = navigator.userAgent.toLowerCase();
mybrowser = {
	version: (browserName.match(/.+(?:rv|it|ra|ie)[\/: ]([\d.]+)/) || [0, '0'])[1],
	safari: /webkit/i.test(browserName) && !this.chrome,
	opera: /opera/i.test(browserName),
        firefox:/firefox/i.test(browserName),
	msie: /msie/i.test(browserName) && !/opera/.test(browserName),
	mozilla: /mozilla/i.test(browserName) && !/(compatible|webkit)/.test(browserName) && !this.chrome,
        chrome: /chrome/i.test(browserName) && /webkit/i.test(browserName) && /mozilla/i.test(browserName)
}