Before the swpagerelsize commits,
(specifically 7c7fdf3e),
the max size was always Prt(). The regression comes if
the RelFrame is a pageFrame (like when the image is
anchored to the page). Then sometimes no maximum is set.

Change-Id: If1e93ce670bd0908eb2d1f89dabbe9861163d29e
Reviewed-on: https://gerrit.libreoffice.org/50034Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>