Change-Id: I387dd7e9237575bae6ebc8a40dc1d1b2b2341960
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