<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="../empty-style.css">
<script>
const executed_during_prerendering = document.prerendering;
// Encode `document.prerendering` into the beacon URL so the test can
// distinguish "script resumed during prerendering (upgrade worked)" from
// "script only resumed after activation". The test asserts that the
// `prerendering=true` variant fires.
navigator.sendBeacon(
    `/iframe-beacon?prerendering=${executed_during_prerendering}`, "");
</script>
</head>
<body>
</body>
</html>