Rename FullscreenElementStack to just Fullscreen

Source/web/ChromeClientImpl.cpp

Index: Source/web/ChromeClientImpl.cpp
diff --git a/Source/web/ChromeClientImpl.cpp b/Source/web/ChromeClientImpl.cpp
index 6f845f54a89dbc5064a0918114540943fbc8ade1..6bb785ac4a5b2d596385a9229aeeb2b397203c17 100644
--- a/Source/web/ChromeClientImpl.cpp
+++ b/Source/web/ChromeClientImpl.cpp
@@ -37,7 +37,7 @@
 #include "core/accessibility/AXObject.h"
 #include "core/accessibility/AXObjectCache.h"
 #include "core/dom/Document.h"
-#include "core/dom/FullscreenElementStack.h"
+#include "core/dom/Fullscreen.h"
 #include "core/dom/Node.h"
 #include "core/events/KeyboardEvent.h"
 #include "core/events/MouseEvent.h"
@@ -222,7 +222,7 @@ Page* ChromeClientImpl::createWindow(LocalFrame* frame, const FrameLoadRequest&
         policy = getNavigationPolicy();
 
     ASSERT(frame->document());
-    FullscreenElementStack::from(*frame->document()).fullyExitFullscreen();
+    Fullscreen::from(*frame->document()).fullyExitFullscreen();
 
     WebViewImpl* newView = toWebViewImpl(
         m_webView->client()->createView(WebLocalFrameImpl::fromFrame(frame), WrappedResourceRequest(r.resourceRequest()), features, r.frameName(), policy, shouldSendReferrer == NeverSendReferrer));