Looks like we forgot to add one hook a few years ago, and now it's revealed while debugging issues described here: https://github.com/w3c/webdriver/issues/1232
Created attachment 334393 [details]
Comment on attachment 334393 [details]
Clearing flags on attachment: 334393
Committed r228887: <https://trac.webkit.org/changeset/228887>
All reviewed patches have been landed. Closing bug.