JS2 has been demerged out of trunk and into the js2-work branch, so
that we can start making some progress again towards the release of
1.16, and the deployment of the current trunk to Wikimedia.
The relevant code is not ready for beta testing, the problems with it
are plain to see on code review. That's why I'm not comfortable with
the idea of promoting it as a core component at this stage.
It's been merged since July (r53282), but there's been very little
work on it by anyone other than Michael and I. So I don't think the
merge has had the desired effect of bringing it to the attention of a
wider developer community.
-- Tim Starling