Updated mediawiki/extensions
Project: mediawiki/extensions/Wikibase  e91a48ea03663973a7739987d5ae69d4e5dba81c

Create more tests for special pages

New test case for ModifyTerm special pages which tests the common
functionalities of those pages. Also moved some code that was used more
than one times into a TestItemHelper class.

Change-Id: Ie13b24a4da9122bfb7c014221e5e8041d7217b3f