20d99c69cb
Since commit 3fb02843, we no longer skip allocation for
results that don't fit the width, and give them a 0x0
allocation instead.
That has the unintended side effect of those children now
being available to keynav. There are cases where we want
0-sized actors to be part of the focus chain (e.g. FocusTrap),
but this isn't one of them, so explicitly exclude 0-sized
children from keynav.
https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/4470
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1916>