'use strict'; promise_test(async (t) => { let iframe = document.createElement('iframe'); await new Promise(resolve => { iframe.src = '../resources/open-in-iframe.html'; iframe.sandbox.add('allow-scripts'); iframe.allow = 'serial'; document.body.appendChild(iframe); iframe.addEventListener('load', resolve); }); await new Promise(resolve => { window.addEventListener('message', t.step_func(messageEvent => { assert_equals(messageEvent.data, 'Success'); resolve(); })); iframe.contentWindow.postMessage({type: 'GetPorts'}, '*'); }); }, 'GetPorts from a sandboxed iframe is valid.');