Fix for bug 252589 (Textbox attribute "multiline" seems broken). r+sr=jst.

content/base/public/nsIDocument.h

@@ -619,6 +619,12 @@ public:
     return mSecurityInfo;
   }
 
+  /**
+   * Returns the default namespace ID used for elements created in this
+   * document.
+   */
+  virtual PRInt32 GetDefaultNamespaceID() const = 0;
+
 protected:
   nsString mDocumentTitle;
   nsCOMPtr<nsIURI> mDocumentURI;

content/xul/content/src/nsXULElement.cpp

@@ -895,11 +895,11 @@ nsXULElement::CloneNode(PRBool aDeep, nsIDOMNode** aReturn)
         NS_ENSURE_TRUE(mSlots, NS_ERROR_UNEXPECTED);
 
         rv = NS_NewXULElement(getter_AddRefs(result), mSlots->mNodeInfo);
-        if (NS_SUCCEEDED(rv)) {
-            // XXX setting document on nodes not in a document so XBL will bind
-            // and chrome won't break. Make XBL bind to document-less nodes!
-            result->SetDocument(mDocument, PR_TRUE, PR_TRUE);
-        }
+        NS_ENSURE_SUCCESS(rv, rv);
+
+        // XXX setting document on nodes not in a document so XBL will bind
+        // and chrome won't break. Make XBL bind to document-less nodes!
+        result->SetDocument(mDocument, PR_TRUE, PR_TRUE);
     }
 
     // Copy attributes

editor/libeditor/base/nsEditor.cpp

@@ -102,6 +102,7 @@
 #include "nsEditorUtils.h"
 #include "nsISelectionDisplay.h"
 #include "nsINameSpaceManager.h"
+#include "nsIHTMLDocument.h"
 
 #define NS_ERROR_EDITOR_NO_SELECTION NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_EDITOR,1)
 #define NS_ERROR_EDITOR_NO_TEXTNODE  NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_EDITOR,2)
@@ -5069,9 +5070,13 @@ nsEditor::CreateHTMLContent(const nsAString& aTag, nsIContent** aContent)
   if (!tag)
     return NS_ERROR_OUT_OF_MEMORY;
 
-  // XXX If editor starts supporting XHTML documents, the kNameSpaceID_None
-  //     should be kNameSpaceID_XHTML for those documents.
-  return doc->CreateElem(tag, nsnull, kNameSpaceID_None, PR_TRUE, aContent);
+  nsCOMPtr<nsIHTMLDocument> htmlDoc = do_QueryInterface(tempDoc);
+  if (htmlDoc) {
+      return doc->CreateElem(tag, nsnull, doc->GetDefaultNamespaceID(),
+                             PR_TRUE, aContent);
+  }
+
+  return doc->CreateElem(tag, nsnull, kNameSpaceID_XHTML, PR_FALSE, aContent);
 }
 
 nsresult