It tries to clear saved user prefs that have long been removed from the default pref file, and it does this every time a new window is launched. It should just be removed, since it's no longer useful.
Created attachment 199760 [details] [diff] [review] patch timebomb.first_launch_time: not used, gone since forever network.cookie.enable: not used network.cookie.denyRemovedCookies: not used in firefox.js network.cookie.enableForOriginatingWebsiteOnly: not used enableForCurrentSessionOnly: not used, needs to be removed from firefox.js as well network.cookie.warnAboutCookies: still appears to be used, but no default browser.search.defaultengine: Referred to by OpenSearch() in browser.js but nonexistent. (bug 203959 is for cleaning that method) print.use_global_printsettings, print.save_print_settings: Reintroduced in bug 118563, so clearing them is a bug...
Comment on attachment 199760 [details] [diff] [review] patch r=mano
mozilla/browser/base/content/browser.js; new revision: 1.523;
Checked in on the branch. mozilla/browser/base/content/browser.js; new revision: 1.479.2.55;
VERIFIED by code inspection.