Actors in clutter are supposed to be re-allocated with
Clutter.AllocationFlags.ABSOLUTE_ORIGIN_CHANGED if they move relative
to the screen, even if they don't move relative to their parent.
Currently this does not work correctly for actors inside containers
with non-northwest gravity. This is probably a fixable bug, but
gravity has messed up other things in the past too, so let's just not
use it.
This change ensures that summary trayicons are re-allocated when the
summary animates, and is part of the fix for
https://bugzilla.gnome.org/show_bug.cgi?id=635695
4c4a703e63