Bring back "notification-dropdown" class for styling and use...

Bring back "notification-dropdown" class for styling and use "js-notification-dropdown" for JavaScript

app/assets/javascripts/notifications_dropdown.js

@@ -19,7 +19,7 @@
       });
       $(document).off('ajax:success', '.notification-form').on('ajax:success', '.notification-form', function(e, data) {
         if (data.saved) {
-          return $(e.currentTarget).closest('.notification-dropdown').replaceWith(data.html);
+          return $(e.currentTarget).closest('.js-notification-dropdown').replaceWith(data.html);
         } else {
           return new Flash('Failed to save new settings', 'alert');
         }

app/views/shared/notifications/_button.html.haml

 - if notification_setting
-  .project-action-button.dropdown.inline
+  .js-notification-dropdown.notification-dropdown.project-action-button.dropdown.inline
     = form_for notification_setting, remote: true, html: { class: "inline notification-form" } do |f|
       = hidden_setting_source_input(notification_setting)
       = f.hidden_field :level, class: "notification_setting_level"