Rename FullscreenElementStack to just Fullscreen

Source/core/page/scrolling/ScrollingCoordinator.cpp

Index: Source/core/page/scrolling/ScrollingCoordinator.cpp
diff --git a/Source/core/page/scrolling/ScrollingCoordinator.cpp b/Source/core/page/scrolling/ScrollingCoordinator.cpp
index 0eca8b643903ec3d866d6378c92eccfde3a88331..8e15171554005cd4fcb98e3f3e787e9dfa61cc6c 100644
--- a/Source/core/page/scrolling/ScrollingCoordinator.cpp
+++ b/Source/core/page/scrolling/ScrollingCoordinator.cpp
@@ -28,7 +28,7 @@
 #include "core/page/scrolling/ScrollingCoordinator.h"
 
 #include "core/dom/Document.h"
-#include "core/dom/FullscreenElementStack.h"
+#include "core/dom/Fullscreen.h"
 #include "core/dom/Node.h"
 #include "core/frame/EventHandlerRegistry.h"
 #include "core/frame/FrameView.h"
@@ -161,7 +161,7 @@ void ScrollingCoordinator::updateAfterCompositingChangeIfNeeded()
         scrollingWebLayer->setBounds(frameView->contentsSize());
         // If there is a fullscreen element, set the scroll clip layer to 0 so main frame won't scroll.
         Document* mainFrameDocument = m_page->deprecatedLocalMainFrame()->document();
-        Element* fullscreenElement = FullscreenElementStack::fullscreenElementFrom(*mainFrameDocument);
+        Element* fullscreenElement = Fullscreen::fullscreenElementFrom(*mainFrameDocument);
         if (fullscreenElement && fullscreenElement != mainFrameDocument->documentElement())
             scrollingWebLayer->setScrollClipLayer(0);
         else