After https://github.com/WebKit/WebKit/pull/9426, the following test fails: imported/w3c/web-platform-tests/shadow-dom/focus-navigation/delegatesFocus-highlight-sibling.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slot-fallback-default-tabindex.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slot-fallback.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slot-nested-2levels.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slot-nested-delegatesFocus.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slot-nested-fallback.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slot-nested.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slot-shadow-in-fallback.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slot-shadow-in-slot.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slot-with-tabindex.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slots-in-slot.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-slots.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-web-component-input-type-radio.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation-with-delegatesFocus.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-navigation.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-nested-slots.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-reverse-unassignable-slot.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-reverse-unassigned-slot.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-unassignable-slot.html imported/w3c/web-platform-tests/shadow-dom/focus-navigation/focus-with-negative-index.html
<rdar://problem/105229933>