Refactor RenderTreeBuilder and expose special <dialog>

Source/core/dom/Element.h

Index: Source/core/dom/Element.h
diff --git a/Source/core/dom/Element.h b/Source/core/dom/Element.h
index c531b068265e146d5922e723a715e783c29a4855..92bc706d3bdf8620d62d8def9e9f867e27200179 100644
--- a/Source/core/dom/Element.h
+++ b/Source/core/dom/Element.h
@@ -479,8 +479,6 @@ public:
     // to event listeners, and prevents DOMActivate events from being sent at all.
     virtual bool isDisabledFormControl() const { return false; }
 
-    virtual bool shouldBeReparentedUnderRenderView(const RenderStyle*) const { return isInTopLayer(); }
-
     bool hasPendingResources() const;
     void setHasPendingResources();
     void clearHasPendingResources();