With tweaks to support firefox 68 from test nodes:
 - build with babel, see jerome/monaco-editor-erp5@cf10f2d5
 - special handling of ResizeObserver that does not exist in Firefox
   68: it is used only for automaticLayout, which is not strictly
   needed. So this feature will not work for firefox 68.

Enable sticky scroll

Set caching manager to must_revalidate_http_cache