When terminating mutter running as a display server, don't try to resize
maximized windows when unmanaging, as at this point, they will have no
MetaWaylandSurface. Originally this was done instead of setting the
net_wm_state to not mess with future window managers, but when we're a
Wayland compositor, this does not matter.
https://bugzilla.gnome.org/show_bug.cgi?id=782156
05d15f8885