DocumentThreadableLoader is using preflight for any non simple CORS request. In case request is handled by SW, no preflighting should happen. If SW is not handling the request, preflighting should happen.
Created attachment 325928 [details] Patch
Created attachment 325964 [details] Build fix
Do we intend to always not allow requests that would require preflight? Why?
Comment on attachment 325928 [details] Patch We really ought to move preflight to the right place.
Comment on attachment 325928 [details] Patch Clearing flags on attachment: 325928 Committed r224439: <https://trac.webkit.org/changeset/224439>
All reviewed patches have been landed. Closing bug.
<rdar://problem/35567451>