Revert "util: cache local GTimeZone"

This reverts commit f597a0a11c.

js/ui/dateMenu.js

@@ -573,11 +573,6 @@ var DateMenuButton = new Lang.Class({
         // https://bugzilla.gnome.org/show_bug.cgi?id=678507
         System.clearDateCaches();
 
-        // To reduce the number of times that Shell opens /etc/localtime on
-        // the main thread to parse timezone info, we cache the result. That
-        // needs to be cleared when we change timezones.
-        Shell.util_clear_timezone_cache();
-
         this._calendar.updateTimeZone();
     },
 

js/ui/environment.js

@@ -118,7 +118,7 @@ function init() {
 
     // Work around https://bugzilla.mozilla.org/show_bug.cgi?id=508783
     Date.prototype.toLocaleFormat = function(format) {
-        return Shell.util_format_now(format);
+        return Shell.util_format_date(format, this.getTime());
     };
 
     let slowdownEnv = GLib.getenv('GNOME_SHELL_SLOWDOWN_FACTOR');