fix dropdowns for mr-versions

app/views/projects/merge_requests/show/_versions.html.haml

@@ -10,11 +10,13 @@
             - else
               version #{version_index(@merge_request_diff)}
           %span.caret
-        %ul.dropdown-menu.dropdown-menu-selectable
+        .dropdown-menu.dropdown-select.dropdown-menu-selectable
           .dropdown-title
-            %span Version
-            %button.dropdown-title-button.dropdown-menu-close
+            %span Version:
+            %button.dropdown-title-button.dropdown-menu-close{aria: {label: "Close"}}
               = icon('times', class: 'dropdown-menu-close-icon')
+          .dropdown-content
+            %ul
               - @merge_request_diffs.each do |merge_request_diff|
                 %li
                   = link_to merge_request_version_path(@project, @merge_request, merge_request_diff), class: ('is-active' if merge_request_diff == @merge_request_diff) do
@@ -38,11 +40,13 @@
               - else
                 #{@merge_request.target_branch}
             %span.caret
-          %ul.dropdown-menu.dropdown-menu-selectable
+          .dropdown-menu.dropdown-select.dropdown-menu-selectable
             .dropdown-title
-              %span Compared with
-              %button.dropdown-title-button.dropdown-menu-close
+              %span Compared with:
+              %button.dropdown-title-button.dropdown-menu-close{aria: {label: "Close"}}
                 = icon('times', class: 'dropdown-menu-close-icon')
+            .dropdown-content
+              %ul
                 - @comparable_diffs.each do |merge_request_diff|
                   %li
                     = link_to merge_request_version_path(@project, @merge_request, @merge_request_diff, merge_request_diff.head_commit_sha), class: ('is-active' if merge_request_diff == @start_version) do