Make Tracekit report correctly angularJS errors

Hi,

I'm pretty sure there are some issues in the way this commit is done (no version bump, etc) but I noticed the stack frames corresponding to something like:

    ReferenceError: xxx is not defined
        at new <anonymous> (http://127.0.0.1:3333/js/app.js:12354:19)
        at invoke (http://127.0.0.1:3333/js/vendor.js:29215:17)
        at Object.instantiate (http://127.0.0.1:3333/js/vendor.js:29226:23)
        at http://127.0.0.1:3333/js/vendor.js:32625:28

were silently skipped in Tracekit, because of the two words "new <anonymous>".

This patch enhances (and in the end, simplifies) the regular expression that was used to decode the stack frames in Chrome. It was checking for 0-1 occurrences of [object], then some non-space chars, then 0-1 occurrences of [as xxx], but included everything in the same capture group.
I just capture what's before the first opening parenthesis.

Other methods (gecko-based detection) seem fine. Test has been added.