I just updated my MediaWiki instance from 1.25 to 1.27.1 (7c4a46b), running on HHVM 3.6.6 (srv) both before and after. Things seem to be working fine overall, but I've noticed that the post-edit confirmation dialog is broken. Instead of appearing center-top with a friendly piece of feedback, it appears in the top left, elongated and empty, and pushing the nav buttons down for a bit until it disappears.
Anyone know what might be wrong?