We renamed some ivars in WKWebViewConfiguration in 276117@main. This broke some poorly behaved apps that were accessing ivars on WKWebViewConfiguration via KVC. We'll temporarily allow these apps to continue to function for backwards compat reasons when linking against an older SDK, but log a fault when it happens. When linking against newer SDKs, Foundation will raise an exception about trying to use KVC against a non-existent property for us.
rdar://125913705
Pull request: https://github.com/WebKit/WebKit/pull/26996
Committed 277266@main (04af542fbc0d): <https://commits.webkit.org/277266@main> Reviewed commits have been landed. Closing PR #26996 and removing active labels.