[Jap2-0]

That's because actual browser development doesn't happen there - that's at https://hg.mozilla.org/mozilla-central/.

Rereading your comment, you're referring more specifically to mobile; I suppose you might have a point there, but when almost everything is in mozilla-central, I'm not sure what you expect to see there (well, extensions, but beyond that) other than UI work.

[iggldiggl]

There are still loads of things that used to work before the rewrite and now don't, plus a number of bugs introduced during the rewrite, and progress in that area is positively glacial.