See the patch.
Created attachment 450013 [details] Patch
Thanks for the patch. If this patch contains new public API please make sure it follows the guidelines for new WebKit2 GTK+ API. See https://trac.webkit.org/wiki/WebKitGTK/AddingNewWebKit2API
Committed r288644 (246454@main): <https://commits.webkit.org/246454@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 450013 [details].