Code Search does not turn up anybody using this method. It isn’t speced, and since r97419 and r97324 you can just construct and initialize a BeforeLoadEvent directly using “new”.
Created attachment 113807 [details] Patch
Comment on attachment 113807 [details] Patch Clearing flags on attachment: 113807 Committed r99389: <http://trac.webkit.org/changeset/99389>
All reviewed patches have been landed. Closing bug.