We were adding null security origins for out-of-process frames in `WebLoaderStrategy::scheduleLoadFromNetworkProcess`, which caused the network process to crash when trying to convert them to a string. Instead, use opaque origins and change `frameAncestorOrigins` to hold Ref, as it can no longer be null.
<rdar://problem/127581415>
Pull request: https://github.com/WebKit/WebKit/pull/28154
Committed 278432@main (f7fb91f7b166): <https://commits.webkit.org/278432@main> Reviewed commits have been landed. Closing PR #28154 and removing active labels.