third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/iframe-register-link-element.html

<script>
var link = document.createElement('link');
link.setAttribute('rel', 'serviceworker');
link.setAttribute('href', 'empty-worker.js');
link.onload = function() {
    top.postMessage('loaded', '*');
}
link.onerror = function(e) {
    top.postMessage('error', '*');
}
document.getElementsByTagName('head')[0].appendChild(link);
</script>