Now the way to disable is about:config or NoScript.
[1] http://news.softpedia.com/newsImage/Firefox-23-Removes-Unused-or-Dangerous-Preferences-from-the-Options-Dialog-2.png/ [2] http://news.softpedia.com/news/Firefox-23-Removes-Unused-or-Dangerous-Preferences-from-the-Options-Dialog-344744.shtml
[3] https://bugzilla.mozilla.org/show_bug.cgi?id=851702
