Need to provide some base defaults for extension web views, like what process pool to use. This is best to do via a WKWebViewConfiguration property on _WKWebExtensionControllerConfiguration.
<rdar://problem/116243665>
Pull request: https://github.com/WebKit/WebKit/pull/18420
Committed 268667@main (11a913369295): <https://commits.webkit.org/268667@main> Reviewed commits have been landed. Closing PR #18420 and removing active labels.