Rename FullscreenElementStack to just Fullscreen

Source/core/dom/RenderTreeBuilder.cpp

Index: Source/core/dom/RenderTreeBuilder.cpp
diff --git a/Source/core/dom/RenderTreeBuilder.cpp b/Source/core/dom/RenderTreeBuilder.cpp
index 2157cd3f01ffd4d72f34cf5a237aa722e3a347eb..7572603e73763b11ab81fd4bb3a7ae75ca1aa8b9 100644
--- a/Source/core/dom/RenderTreeBuilder.cpp
+++ b/Source/core/dom/RenderTreeBuilder.cpp
@@ -29,7 +29,7 @@
 #include "core/HTMLNames.h"
 #include "core/SVGNames.h"
 #include "core/css/resolver/StyleResolver.h"
-#include "core/dom/FullscreenElementStack.h"
+#include "core/dom/Fullscreen.h"
 #include "core/dom/Node.h"
 #include "core/dom/Text.h"
 #include "core/rendering/RenderFullScreen.h"
@@ -132,7 +132,7 @@ void RenderTreeBuilder::createRendererForElementIfNeeded()
     element->setRenderer(newRenderer);
     newRenderer->setStyle(&style); // setStyle() can depend on renderer() already being set.
 
-    if (FullscreenElementStack::isActiveFullScreenElement(*element)) {
+    if (Fullscreen::isActiveFullScreenElement(*element)) {
         newRenderer = RenderFullScreen::wrapRenderer(newRenderer, parentRenderer, &element->document());
         if (!newRenderer)
             return;