Introduce FullscreenElementStack::fullyExitFullscreen()

Source/web/FullscreenController.cpp

Index: Source/web/FullscreenController.cpp
diff --git a/Source/web/FullscreenController.cpp b/Source/web/FullscreenController.cpp
index 94a9ee5766d44f5826590a1ccc3f39ee244a9609..a18101de654d79c6dd6a06de41e8c853cd9a6373 100644
--- a/Source/web/FullscreenController.cpp
+++ b/Source/web/FullscreenController.cpp
@@ -117,10 +117,10 @@ void FullscreenController::willExitFullScreen()
         if (!fullscreen)
             return;
         if (fullscreen->isFullScreen(*doc)) {
-            // When the client exits from full screen we have to call webkitCancelFullScreen to
-            // notify the document. While doing that, suppress notifications back to the client.
+            // When the client exits from full screen we have to call fullyExitFullscreen to notify
+            // the document. While doing that, suppress notifications back to the client.
             m_isCancelingFullScreen = true;
-            fullscreen->webkitCancelFullScreen();
+            fullscreen->fullyExitFullscreen();
             m_isCancelingFullScreen = false;
             fullscreen->webkitWillExitFullScreenForElement(0);
             if (RuntimeEnabledFeatures::overlayFullscreenVideoEnabled() && m_webViewImpl->layerTreeView())