Refactor RenderTreeBuilder and expose special <dialog>

Source/core/html/HTMLDialogElement.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 183 matching lines @@
 void HTMLDialogElement::defaultEventHandler(Event* event)
 {
     if (event->type() == EventTypeNames::cancel) {
         closeDialog();
         event->setDefaultHandled();
         return;
     }
     HTMLElement::defaultEventHandler(event);
 }
 
-bool HTMLDialogElement::shouldBeReparentedUnderRenderView(const RenderStyle* style) const
-{
-    if (style && style->position() == AbsolutePosition)
-        return true;
-    return Element::shouldBeReparentedUnderRenderView(style);
-}
-
 } // namespace WebCore