diff --git a/mozilla/js/src/xpconnect/idl/nsIXPCScriptable.idl b/mozilla/js/src/xpconnect/idl/nsIXPCScriptable.idl
index 0bbe31d377c..6409d958601 100644
--- a/mozilla/js/src/xpconnect/idl/nsIXPCScriptable.idl
+++ b/mozilla/js/src/xpconnect/idl/nsIXPCScriptable.idl
@@ -67,7 +67,7 @@ interface nsIXPCScriptable : nsISupports
     const PRUint32 CLASSINFO_INTERFACES_ONLY        = 1 << 23;
     const PRUint32 ALLOW_PROP_MODS_DURING_RESOLVE   = 1 << 24;
     const PRUint32 ALLOW_PROP_MODS_TO_PROTOTYPE     = 1 << 25;
-
+    const PRUint32 DONT_SHARE_PROTOTYPE             = 1 << 26;
 
     readonly attribute string   className;
     readonly attribute PRUint32 scriptableFlags;