Comment 16 for bug 352950

Upstream confirmed that this patch should fix the problem. I was unable to confirmed it because I can't reproduce it, and no one from the bug reported that the patch fix the problem (or the contrary).
Anyway, I think it's save to add it because it was apply upstream 12 days ago without negative feedback. It will also be part of the next bugfix-only release of Avant-window-navigator.