[orca-list] I think I've gotten the rest of the Alt+Tab workaround bugs fixed

[Joanmarie Diggs <jdiggs igalia com>]

Hey all.

As some of you are aware, there were a number of cases in which you
couldn't down arrow in Firefox, but if you Alt+Tabbed out of Firefox and
back in, things started working. You reported that some earlier changes
I made fixed many of those issues, but not all. Now, thanks to Attila's
persistence in finding me test cases, I believe I found a way to fix the
rest of them -- and it's a way that won't hurt performance. Please test
master and let me know.

Thanks!
--joanie (waiting with her fingers crossed)