Make sure to export autostyles from inside frames anchored to page
These frames need to export content when collecting autostyles, too.
Regression after commit
69ed893087f89d176a5ec4b263ce8d75774be72b
(tdf#160253: fix list identifier export decision code, 2024-04-24).
Change-Id: If036cab9327e33d32f494fc765bae8e2d685907c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/166650
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>