since (I believe)

commit 34d76029
Date:   Wed Nov 9 15:22:43 2016 +0200

    tdf#55469 Consistent line spacing across platforms

the point of that was to have the same line spacing on all platforms
to fix the cairo text layout bounds to use the same algorithm as
the generic text layout

Change-Id: I26d3dec8354a9eac1423557f7d52a08f37c8843c
Reviewed-on: https://gerrit.libreoffice.org/40364Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>