The Tor Browser / file revision

 Cu.import("resource://gre/modules/Services.jsm");

 function makeURI(str) {

     return Components.classes["@mozilla.org/network/io-service;1"]

                      .getService(Components.interfaces.nsIIOService)

                      .newURI(str, null, null);

 }

 function run_test() {

     // Allow all cookies.

     Services.prefs.setIntPref("network.cookie.cookieBehavior", 0);

     var serv =   Components.classes["@mozilla.org/cookieService;1"]

                            .getService(Components.interfaces.nsICookieService);

     var uri = makeURI("http://example.com/");

     // Try an expiration time before the epoch

     serv.setCookieString(uri, null, "test=test; path=/; domain=example.com; expires=Sun, 31-Dec-1899 16:00:00 GMT;", null);

     do_check_eq(serv.getCookieString(uri, null), null);

     // Now sanity check

     serv.setCookieString(uri, null, "test2=test2; path=/; domain=example.com;", null);

     do_check_eq(serv.getCookieString(uri, null), "test2=test2");

 }