third_party/web_platform_tests/workers/non-automated/application-cache-dedicated.html

<!doctype html>
<html manifest=cache.manifest>
<title>cache manifest</title>
<p>Script did not run.</p>
<p>To run this test again, delete private data and then load this test again.</p>
<script>
var p = document.querySelector('p');
if (sessionStorage.testHasBeenLoadedBefore) {
  var worker = new Worker('application-cache-dedicated.js');
  worker.onmessage = function(e) {
    p.textContent = 'PASS';
  }
  setTimeout(function(){
    if (p.textContent != 'PASS')
      p.textContent = 'FAIL (got no message from worker)';
  }, 250);
} else {
  sessionStorage.testHasBeenLoadedBefore = true;
  p.textContent = 'Enable offline mode and then reload this test. It should say PASS.';
}
</script>