ContentHandlerTest: Use dataProvider

Changing a global 3 times in a test is bad, using dataProvider for two
tests and split another in 3, because there are different.

Using mwglobals to set the globals, than restoring is done
automatically.

Change-Id: Ie0f9ce0be39e457d18752e905d6deeb1803cb4c3
Merge "ContentHandlerTest: Use dataProvider"