D15344: Fix isNull check for RegularArea

[Albert Astals Cid]

aacid accepted this revision.
This revision is now accepted and ready to land.

REPOSITORY
  R223 Okular

BRANCH
  fix_regulararea_isnull

REVISION DETAIL
  https://phabricator.kde.org/D15344

To: tobiasdeiminger, aacid
Cc: okular-devel, ngraham, aacid