How to confirm popup using requestStorageAccess.

Hi

I'm using IOS12 beta 9 and want to confirm popup raising while using requestStorageAccess().

It is described as part of ITP2.0 https://webkit.org/blog/8311/intelligent-tracking-prevention-2-0/.

I wrote Javascript and see it with safari but requestStorageAccess always return true and I can't confirm pop.

Is there anyway to confirm popup or I have to wati further update of ios12 beta?

<script>
function makeRequestWithUserGesture() {
  var promise = document.requestStorageAccess();
  promise.then(
  function () {
  // Storage access was granted.
  // Check whether the user is logged in.
  // If not, do a popup to log the user in.
  },
  function () {
  // Storage access was denied.
  }
  );
}
</script>
<button onclick="makeRequestWithUserGesture()">Play video</button>