bug 84188, Need to migrate existing localizable string preferences to a new pref type, r=tao, sr=blake

suite/common/pref/pref-locales.xul

@@ -61,7 +61,7 @@
 
     function SwitchContentPack()
     {
-      var oldContentPack = parent.hPrefWindow.getPref( "string", "general.useragent.contentlocale");
+      var oldContentPack = parent.hPrefWindow.getPref( "localizedstring", "general.useragent.contentlocale");
       var newContentPack;
 
       try {