The callback for ready function may be added as event handler of localized[1]. If it is this case, the callback function is called again when user changes the language in settings app. So, I preserve the if condition.

[1] https://github.com/mozilla-b2g/gaia/blob/0505d8adb0a76556584e302cd524c0bed41445f9/shared/js/l10n.js#L1225