Fullscreen UIScene adjustments are not reverted if the Web Content pr…

…ocess crashes while in fullscreen

https://bugs.webkit.org/show_bug.cgi?id=253216
rdar://106107254

Reviewed by Aditya Keerthi.

* Source/WebKit/UIProcess/ios/fullscreen/WKFullScreenWindowControllerIOS.mm:
(-[WKFullScreenWindowController _exitFullscreenImmediately]):
Perform the fullscreen transition without animation if exiting fullscreen "immediately",
which happens in cases such as Web Content process crash or WKWebView unparenting.
This ensures that all of the scene/window cleanup work happens even if we don't go through
the usual animated dismissal path.

Canonical link: https://commits.webkit.org/261051@main

Source/WebKit/UIProcess/ios/fullscreen/WKFullScreenWindowControllerIOS.mm

@@ -1082,6 +1082,13 @@ - (void)_exitFullscreenImmediately
     if (page)
         page->setSuppressVisibilityUpdates(true);
 
+#if ENABLE(FULLSCREEN_WINDOW_EFFECTS)
+    [UIView performWithoutAnimation:^{
+        CompletionHandler<void()> completionHandler = []() { };
+        performFullscreenTransition(_lastKnownParentWindow.get(), _window.get(), _parentWindowState.get(), false, WTFMove(completionHandler));
+    }];
+#endif
+
     [self _reinsertWebViewUnderPlaceholder];
 
     if (auto* manager = self._manager) {