Fix bug #7641: Freeze when removing itemized first paragraph

Fix bug #7641: Freeze when removing itemized first paragraph

Text::outerFont looks recursively for paragraphs before the current one
which has a lower depth. If such a paragraph cannot be found, depthHook
and outerHook return the current paragraph. As such, we end up in an
infinite loop. So, if we find a par_depth that was the same as the
previous one, we apparently can't find a suitable paragraph and we should
quit the loop.