<!DOCTYPE html>
<head>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<body>
</body>
<script>
promise_test(async () => {
  performance.clearResourceTimings()

  // Create child iframe.
  const childFrame = document.createElement('iframe')
  childFrame.src = "../resources/child-frame.html"
  document.body.appendChild(childFrame)

  // wait until the child frame's onload event fired
  await new Promise(r => childFrame.addEventListener("load", 