We're timing out on the srcdoc subtests of the named WPT. After playing with this a little bit I believe this is because when we navigate back in history with window.history.back() we aren't navigating back to the srcdoc but instead to the document before we set srcdoc attribute. I reproduced this by reducing the WPT subtest to this: message.html: -------------- <!DOCTYPE html> <script> top.postMessage("ready", "*"); </script> message-and-back.html: -------------- <!DOCTYPE html> <script> top.postMessage({msg:"message-and-back"}, "*"); window.history.back(); </script> srcdoc.html: -------------- <!DOCTYPE html> <script> const message_from = (starts_with) => { return new Promise(resolve => { window.addEventListener('message', msg => { if (!starts_with || msg.data.msg.startsWith(starts_with)) resolve(msg.data.msg); }); }); }; const htmlPayload = ` <!DOCTYPE html> <script> function ready() { top.postMessage({msg:'sdoc'}, '*'); } <\/script> <body onpageshow='ready()'> <h1>Hello world!<\/h1> <\/body> <\/html> `; async function run() { let i = document.createElement("iframe"); document.body.appendChild(i); i.contentWindow.location = "message.html"; await message_from("ready"); i.srcdoc = html_payload; await message_from("sdoc"); i.contentWindow.location = "message-and-back.html"; await message_from("message-and-back"); await message_from("sdoc"); // <-- this is where WPT hangs and times out } </script> <body onload="run()"></body> If I serve and navigate to srcdoc.html and check the inspector, the iframe has the expected srcdoc attribute but the document in the frame is actually the content of message.html I think we're either mistakenly not putting the srcdoc entry in history or the spec tells us not to and the WPT needs to change. I'll need to take a closer look.
<rdar://problem/101055087>
It looks like there's spec work to be done w.r.t srcdoc in history. See https://github.com/whatwg/html/issues/6809