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), sorry in advance.
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" and "<anonymous>" next to each other in the first frame.

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.