[DOM4] Doctypes now always have a node document and can be moved across document boundaries

Source/core/dom/ContainerNode.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 156 matching lines @@
         return true;
     }
 
     // This should never happen, but also protect release builds from tree corruption.
     ASSERT(!newChild->isPseudoElement());
     if (newChild->isPseudoElement()) {
         es.throwDOMException(HierarchyRequestError);
         return false;
     }
 
-    if (newChild->inDocument() && newChild->isDocumentTypeNode()) {
-        es.throwDOMException(HierarchyRequestError);
-        return false;
-    }
     if (containsConsideringHostElements(newChild, newParent)) {
         es.throwDOMException(HierarchyRequestError);
         return false;
     }
 
     if (oldChild && newParent->isDocumentNode()) {
         if (!toDocument(newParent)->canReplaceChild(newChild, oldChild)) {
             es.throwDOMException(HierarchyRequestError);
             return false;
         }
@@ skipping 861 matching lines @@
         return true;
 
     if (node->isElementNode() && toElement(node)->shadow())
         return true;
 
     return false;
 }
 #endif
 
 } // namespace WebCore