[ticket/12061] Fix keyboard shortcut in firefox

PHPBB3-12061
Merge remote-tracking branch 'Elsensee/ticket/12061' into develop-olympus

* Elsensee/ticket/12061:
  [ticket/12061] Fix keyboard shortcut in firefox
Merge branch 'develop-olympus' into develop

* develop-olympus:
  [ticket/12061] Fix keyboard shortcut in firefox

Conflicts:
	phpBB/styles/prosilver/template/overall_footer.html