Bug 14813: Fix encoding issues on editing help pages

Bug 14813: Fix encoding issues on editing help pages

It has been introduced by bug 11944.

Test plan:
1/ Install and set the fr-FR language (or ar-Arab).
2/ Go on the help page and edit it.
3/ The textarea should not contain encoding issues with this patch.

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@unc.edu.ar>
(cherry picked from commit d671b8661cf02d8b039eb5230ab732fd1fde2301)
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>