Change-Id: I9f48310a405844c61aa6619e6fc28cf3bcbb9619
Core module reduces the amount of duplicated code across skins, see core change-id: I8ecbc827f2b05aec79401ac4962fcc15387c8ad8. Change-Id: Icb4683f0382c9b2984db5293cd01f715c5320552
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