fixed gecko regExp for parding more complicated stack lines

Issue https://github.com/getsentry/raven-js/issues/249

I got stack like this in Firefox:
```
.events["click [data-test]"]@http://example.com/user/views/UserView.js:23:17
jQuery.event.dispatch@http://example.com/vendor/jquery/jquery.js:4641:1
jQuery.event.add/elemData.handle@http://example.com/vendor/jquery/jquery.js:4309:1
```

But in Sentry I got only 2 lines:
```
jQuery.event.dispatch@http://example.com/vendor/jquery/jquery.js:4641:1
jQuery.event.add/elemData.handle@http://example.com/vendor/jquery/jquery.js:4309:1
```

This pull request fixes this issue.