Plumb SecurityOrigin and ScopedURL
<rdar://problem/103929930>
Pull request: https://github.com/WebKit/WebKit/pull/8258
Pull request: https://github.com/WebKit/WebKit/pull/15907
Committed 266692@main (f72ca735a42e): <https://commits.webkit.org/266692@main> Reviewed commits have been landed. Closing PR #16449 and removing active labels.