LayoutTests/http/tests/site-isolation/https-load.html

<!-- webkit-test-runner [ SiteIsolationEnabled=true ] -->
<script>
if (window.testRunner) {
    testRunner.dumpAsText();
    testRunner.waitUntilDone();
}
addEventListener("message", (event) => {
    alert("received '" + event.data + "'");
    testRunner.notifyDone();
});
</script>
<iframe src="https://localhost:8443/site-isolation/resources/fetch-https.html" id="frame"></iframe>