Got a warning when working on something unrelated: apparently some of the objects we wrap with WKObject require 16-byte alignment on my system (such as WebFrameProxy) but we are running its constructor on an 8-byte aligned address. I believe that changing minimumObjectAlignment to 16 should cover everything that we use, but I have a patch with something that's IMO more portable than a hardcoded number that I'll attach as soon as I can get around to it.
Created attachment 373552 [details]
Looks like Tim Horton did this in Bug 179518.
Oh dear. That was watch bringup, my memory is not great.
Comment on attachment 373552 [details]
Clearing flags on attachment: 373552
Committed r247281: <https://trac.webkit.org/changeset/247281>
All reviewed patches have been landed. Closing bug.