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

Source/core/dom/ContainerNode.cpp

Index: Source/core/dom/ContainerNode.cpp
diff --git a/Source/core/dom/ContainerNode.cpp b/Source/core/dom/ContainerNode.cpp
index d5a36405792101cabc2bae92bc570d606cce3d18..c184a5e8752c2a28e52e087e3eec5712e62102cc 100644
--- a/Source/core/dom/ContainerNode.cpp
+++ b/Source/core/dom/ContainerNode.cpp
@@ -174,10 +174,6 @@ static inline bool checkAcceptChild(ContainerNode* newParent, Node* newChild, No
         return false;
     }
 
-    if (newChild->inDocument() && newChild->isDocumentTypeNode()) {
-        es.throwDOMException(HierarchyRequestError);
-        return false;
-    }
     if (containsConsideringHostElements(newChild, newParent)) {
         es.throwDOMException(HierarchyRequestError);
         return false;