Fix dumb copy-paste bug jst pointed out, whose symptom bz reported (r+sr=jst, a=me).

js/src/xpconnect/idl/nsIXPConnect.idl

@@ -437,7 +437,7 @@ interface nsIXPConnect : nsISupports
                   in PRUint32     aFlags);
 
     const PRUint32 INIT_JS_STANDARD_CLASSES  = 1 << 0;
-    const PRUint32 FLAG_SYSTEM_GLOBAL_OBJECT = 1 << 0;
+    const PRUint32 FLAG_SYSTEM_GLOBAL_OBJECT = 1 << 1;
 
     /**
     * wrapNative will create a new JSObject or return an existing one.