* Fix up one last use of global config vars in this class.
Other places in this class already used $rl->getConfig().
This way we don't inherit all of MediaWikiTestCase.
* Add unit tests covering all of ResourceLoaderContext
except expandModuleNames and getImageObj (tested in better
places already with the right @covers).
* Increase coverage for expandModuleNames(), add missing case
of when modules are not in alphabetical order.
Change-Id: Id19b084d37a6c3a77b36e03509adffb6b156fee1
