Implement OOUI "display format" in MediaWiki's HTMLForm. This is necessary to make special pages using HTMLForm (such as Special:PasswordReset) OOUI-enabled.
It doesn't cause any visible changes by itself, as we haven't switched any actual forms to the new implementation yet. That could use a notice, when it happens. We should send a quick note to wikitech-l that this is available now, though.