Rename FullscreenElementStack to just Fullscreen

Source/core/css/SelectorChecker.cpp

Index: Source/core/css/SelectorChecker.cpp
diff --git a/Source/core/css/SelectorChecker.cpp b/Source/core/css/SelectorChecker.cpp
index d95fca32c9c184873755a44150577c07a2ec9680..ef8c9c9f8ffae75b3f6bb71792471e8ff0b3ec3e 100644
--- a/Source/core/css/SelectorChecker.cpp
+++ b/Source/core/css/SelectorChecker.cpp
@@ -33,7 +33,7 @@
 #include "core/css/SiblingTraversalStrategies.h"
 #include "core/dom/Document.h"
 #include "core/dom/ElementTraversal.h"
-#include "core/dom/FullscreenElementStack.h"
+#include "core/dom/Fullscreen.h"
 #include "core/dom/NodeRenderStyle.h"
 #include "core/dom/StyleEngine.h"
 #include "core/dom/Text.h"
@@ -855,7 +855,7 @@ bool SelectorChecker::checkOne(const SelectorCheckingContext& context, const Sib
             // context's Document is in the fullscreen state has the 'full-screen' pseudoclass applied.
             if (isHTMLFrameElementBase(element) && element.containsFullScreenElement())
                 return true;
-            if (FullscreenElementStack* fullscreen = FullscreenElementStack::fromIfExists(element.document())) {
+            if (Fullscreen* fullscreen = Fullscreen::fromIfExists(element.document())) {
                 if (!fullscreen->webkitIsFullScreen())
                     return false;
                 return element == fullscreen->webkitCurrentFullScreenElement();
@@ -866,7 +866,7 @@ bool SelectorChecker::checkOne(const SelectorCheckingContext& context, const Sib
         case CSSSelector::PseudoFullScreenDocument:
             // While a Document is in the fullscreen state, the 'full-screen-document' pseudoclass applies
             // to all elements of that Document.
-            if (!FullscreenElementStack::isFullScreen(element.document()))
+            if (!Fullscreen::isFullScreen(element.document()))
                 return false;
             return true;
         case CSSSelector::PseudoInRange: