Merge branch 'ee-6646-dropdowns-css' into 'master'

Removes EE differences for dropdowns.scss

Closes #6646

See merge request gitlab-org/gitlab-ee!10404

app/assets/stylesheets/framework/dropdowns.scss

@@ -26,7 +26,7 @@
 
 .show.dropdown {
   .dropdown-menu,
-  .dropdown-menu {
+  .dropdown-menu-nav {
     @include set-visible;
     min-height: $dropdown-min-height;
     max-height: $dropdown-max-height;
@@ -417,7 +417,7 @@
 
 .filtered-search-box-input-container {
   .dropdown-menu,
-  .dropdown-menu {
+  .dropdown-menu-nav {
     max-width: 280px;
   }
 }
@@ -813,7 +813,7 @@
 
   header.navbar-gitlab .dropdown {
     .dropdown-menu,
-    .dropdown-menu {
+    .dropdown-menu-nav {
       width: 100%;
       min-width: 100%;
     }