Update markup in merge_requests/invalid.html.haml

app/views/projects/merge_requests/invalid.html.haml

@@ -8,7 +8,9 @@
   = render "projects/merge_requests/mr_box"
 
   .gl-alert.gl-alert-danger
+    .gl-alert-container
       = sprite_icon('error', size: 16, css_class: 'gl-icon gl-alert-icon gl-alert-icon-no-title')
+      .gl-alert-content{ role: 'alert' }
         %p
           We cannot render this merge request properly because
           - if @merge_request.for_fork? && !@merge_request.source_project