tdf#134746 sw: fix redline hiding of at-char fly on empty paragraphs
If a merged paragraph has no extents, a fly anchored at the start or at
the end should be shown.
(regression from
28b77c89dfcafae82cf2a6d85731b643ff9290e5)
Change-Id: I78135f3c033cf08aad81c86b0ac693528e3f3f8e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/100543
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@cib.de>
(cherry picked from commit
f3cb59c46398b3a0646b8b374d5626f715fa6884)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/100703
Reviewed-by: Caolán McNamara <caolanm@redhat.com>