Make process selection synchronous when we process-swap on navigation. This will make caching processes per RegistrableDomain easier for site isolation, since we want all iframes from a given registrable domain to be loaded in the same process.
<rdar://problem/107966850>
Pull request: https://github.com/WebKit/WebKit/pull/12681
Committed 262913@main (563b555f7bbf): <https://commits.webkit.org/262913@main> Reviewed commits have been landed. Closing PR #12681 and removing active labels.