<!DOCTYPE html>
<script>
  let draft = [];
  var resolve_manual_promise;
  let manual_promise =
    new Promise(resolve => resolve_manual_promise = resolve).then(() => draft.push('microtask'));

  let resolve_message_promise;
  let message_promise = new Promise(resolve => resolve_message_promise = resolve);
  function handle_message(event) {
    draft.push('message');
    resolve_message_promise();
  }

  var result = Promise.all([manual_promise, message_promise]).then(() => draft);
</script>

<script src="empty.js?key=start"></script>