<!DOCTYPE html> <script src="/resources/testharness.js"></script> <script src="/resources/testharnessreport.js"></script> <script> promise_test(async (t) => { assert_implements("HTMLPortalElement" in self); let hostWindow = window.open(); assert_equals(hostWindow.location.href, "about:blank"); let portal = hostWindow.document.createElement("portal"); portal.src = "resources/simple-portal.html"; hostWindow.document.body.appendChild(portal); await promise_rejects_dom(t, "InvalidStateError", hostWindow.DOMException, portal.activate()); }, "about:blank cannot host a portal"); </script>