Add class to use in JS and tests

app/views/projects/protected_branches/shared/_create_protected_branch.html.haml

-= form_for [@project.namespace.becomes(Namespace), @project, @protected_branch] do |f|
+= form_for [@project.namespace.becomes(Namespace), @project, @protected_branch], html: { class: 'new-protected-branch js-new-protected-branch' } do |f|
   .panel.panel-default
     .panel-heading
       %h3.panel-title

app/views/projects/protected_tags/shared/_tags_list.html.haml

-.panel.panel-default.protected-tags-list
+.panel.panel-default.protected-tags-list.js-protected-tags-list
   - if @protected_tags.empty?
     .panel-heading
       %h3.panel-title