[orca-list] Landed some non-trivial changes to Orca's web support

[Joanmarie Diggs <jdiggs igalia com>]

Hey all.

I just did some clean-up of Orca's web support, specifically around
caret navigation. I hope you won't find any regressions and instead find
things a bit snappier. But authors + Gecko = all bets are off. ;) Thus
testing of master will be most appreciated.

In addition, I took a stab and solving the problem where off-screen link
text is presented by word rather than line. A good example is
Amazon.com. Gecko gives the line text to us as single words. For now, in
order to make the problem suck less, you'll get the link's name. That
can lead to a rather long line if the authors make a ginormous link, but
I think it beats the by-word experience. Later I'll see about making
further changes to improve the situation, but hopefully what I've done
in the meantime is to your liking.

Please let me know on both fronts (regression and off-screen links) what
you find.

Thanks in advance!
--joanie