<!DOCTYPE html>
<meta charset="utf-8">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/helpers.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>

<body>
<script>
"use strict";
promise_test(async t => {
  const sentinelIframe = await setupSentinelIframe(t);
  const startingHistoryLength = history.length;

  const code = `
    window.onpageshow = () => {
      c