Updated mediawiki/core Project: mediawiki/extensions/Echo rECHO19d8c4adca02

Don't load oojs-ui.styles on every page

We don't really need it to render the no-JS version
of the notification badges (the only rule we were missing
was background-repeat: no-repeat;) and it significantly
increased the amount of render-blocking CSS.

This means we do need to call setupOOUI() ourselves
in order for our get_class( OOUI\Theme::singleton() ) hack
to keep working.

Bug: T112401
Change-Id: I148f8ac19dfe62cc84abe03e1a2ff00683d515c1
(cherry picked from commit b046a1062d0210f5ebc76c316c08d247079b82a1)