[ticket/11733] Add browse test for feed.php

PHPBB3-11733
[ticket/11733] Fix "Illegal offset type" Warning caused by overall feed

PHPBB3-11733
Merge remote-tracking branch 'nickvergessen/ticket/11733' into develop

* nickvergessen/ticket/11733:
  [ticket/11733] Fix "Illegal offset type" Warning caused by overall feed
  [ticket/11733] Add browse test for feed.php