diff -r 000000000000 -r 6474c204b198 dom/interfaces/core/nsIDOMUserDataHandler.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/interfaces/core/nsIDOMUserDataHandler.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,26 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "domstubs.idl"
+#include "nsIVariant.idl"
+
+
+// Introduced in DOM Level 3:
+
+[scriptable, function, uuid(91afebdd-a201-4db0-b728-9d59580f0cfd)]
+interface nsIDOMUserDataHandler : nsISupports
+{
+  // OperationType
+  const unsigned short      NODE_CLONED                    = 1;
+  const unsigned short      NODE_IMPORTED                  = 2;
+  const unsigned short      NODE_DELETED                   = 3;
+  const unsigned short      NODE_RENAMED                   = 4;
+  const unsigned short      NODE_ADOPTED                   = 5;
+
+  void               handle(in unsigned short operation,
+                            in DOMString key,
+                            in nsIVariant data,
+                            in nsIDOMNode src,
+                            in nsIDOMNode dst);
+};