Change-Id: I2e693e55d4a7bc03cbef770efdc69678fde9e5be
This is the final step of the process described at <https://www.mediawiki.org/wiki/Separating_skins_from_core_MediaWiki>. Corresponding core change: Idfc38503. Change-Id: I83b1efb4a489254c76e0cbda72ff34efa3d41261