Created attachment 446939 [details]
Video of the issue
On all Discourse sites, when clicking on the account image, which typically shows the various account options, it instead flashes the options view and then scrolls up. Repeated clicking will eventually scroll up the entire thread and then properly show the account options. This occurs on all of the Discourse sites I've tested. A video is attached. It seemed to start about a month ago, so perhaps STP 132 or 130. Regular Safari works fine on the same sites.
Regressed at https://trac.webkit.org/changeset/283546
Reverted in bug 234844 and confirmed that this is now fixed. I will work on re-implementing the reverted behavior without the bug.