`nsILocalFile` should be replaced with `nsIFile`.
Warning: Starting with Gecko 14,
nsILocalFile inherits all functions and attributes from
nsIFile, meaning that you no longer need to use
nsILocalFile. If your add-on doesn't support versions older than 14, you should use
nsIFile instead of
See bug https://bugzilla.mozilla.org/show_bug.cgi?id=682360 for more information.