Resync XHR Web Platform Tests from upstream 44dd29fb0d.
Created attachment 353500 [details] Patch
Comment on attachment 353500 [details] Patch Clearing flags on attachment: 353500 Committed r237646: <https://trac.webkit.org/changeset/237646>
All reviewed patches have been landed. Closing bug.
<rdar://problem/45709393>