* Part of https://gerrit.wikimedia.org/r/#/c/151395/ Change-Id: Iae873906abcd8b2a986e5f728f0ce207256de770
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: I84fcf7ce6385b8323544cafe6912a00f1886d20d