Merge branch 'fix-master-stylelint-duplicate-class-dropdowns-scss' into 'master'

Remove duplicate dropdown class in dropdowns.scss

See merge request gitlab-org/gitlab-ee!9558

app/assets/stylesheets/framework/dropdowns.scss

@@ -404,7 +404,7 @@
 }
 
 .droplab-dropdown .dropdown-menu,
-.droplab-dropdown .dropdown-menu {
+.droplab-dropdown .dropdown-menu-nav {
   display: none;
   opacity: 1;
   visibility: visible;