Guard against pref_show_stylesheets being bad in UnloggedUser case.
Guard against pref_show_stylesheets being bad in UnloggedUser case.

florenceyeun/reddit-plugin-liveupdate,madbook/reddit-plugin-liveupdate,sim642/reddit-plugin-liveupdate,florenceyeun/reddit-plugin-liveupdate,florenceyeun/reddit-plugin-liveupdate,sim642/reddit-plugin-liveupdate,madbook/reddit-plugin-liveupdate,madbook/reddit-plugin-liveupdate,sim642/reddit-plugin-liveupdate