Rather than having get_stream_li() look up stream id using
stream name, we force the callers to pass in the stream id.
This adds an extra line to most of the callers for now, but
this will eventually change as we fix some of the callers to
have their callers pass in stream_id.
In places where we now call stream_data.get_stream_id() to
get the stream id, we will be more resilient toward stream
renamings, at least until the next reload, since
stream_data.get_stream_id() can resolve old names that
are stored when we process stream-rename events.
The function modals.is_active() can see if modals are open
without having to look at the DOM. This should make it snappier
to type in the compose box. Even if the speedup is pretty minor,
not having to worry about jQuery slowness should make it easier
to diagnose future compose box issues.
The new function gets used in other places, too, where performance
isn't so much an issue.
Steve Howell