Add "offline" key

www/common/toolbar.js

@@ -1395,7 +1395,8 @@ MessengerUI, Messages) {
             toolbar.isErrorState = bool; // Stop kickSpinner
             toolbar.title.toggleClass('cp-toolbar-unsync', bool); // "read only" next to the title
             if (bool && toolbar.spinner) {
-                toolbar.spinner.text("OFFLINE"); // XXX
+                Messages.offline = "OFFLINE"; // XXX
+                toolbar.spinner.text(Messages.offline);
             } else {
                 kickSpinner(toolbar, config);
             }