Replace RenderFullScreen with top layer

Source/core/dom/Document.h

Index: Source/core/dom/Document.h
diff --git a/Source/core/dom/Document.h b/Source/core/dom/Document.h
index b516533480588df12a81a06ddff15dcdf1485704..da29b814ccf3289ff7f7addd62bd241820bc4115 100644
--- a/Source/core/dom/Document.h
+++ b/Source/core/dom/Document.h
@@ -988,6 +988,8 @@ public:
     void addToTopLayer(Element*, const Element* before = 0);
     void removeFromTopLayer(Element*);
     const Vector<RefPtr<Element> >& topLayerElements() const { return m_topLayerElements; }
+    void addToModalDialogStack(HTMLDialogElement*);
+    void removeFromModalDialogStack(HTMLDialogElement*);
     HTMLDialogElement* activeModalDialog() const;
 
     const Document* templateDocument() const;
@@ -1253,6 +1255,7 @@ private:
     bool m_hasFullscreenElementStack; // For early return in FullscreenElementStack::fromIfExists()
 
     Vector<RefPtr<Element> > m_topLayerElements;
+    HTMLDialogElement* m_activeModalDialog;
 
     int m_loadEventDelayCount;
     Timer<Document> m_loadEventDelayTimer;