joint_session_history/002.html: third subtest expects document.open() to add a history entry and fire pageshow (pre whatwg/html#3946) #63099

joint_session_history/002.html times out in every engine. wpt.fyi on 2026-09-30: Chrome 154 2/3 TIMEOUT, Firefox 157 2/3 TIMEOUT, Safari TP 253 0/3 TIMEOUT.

Its third subtest, "Navigating second iframe" in 002-1.html, does the following:

1. Calls iframe.contentDocument.open(), write() and close().
2. Waits for the written content's onpageshow to call parent.frameloaded().
3. Asserts history.length == 2.

That is the pre-2018 document.open() model. Since whatwg/html#3946 (part of whatwg/html#3818), document.open() creates no new Document, fires no pageshow and adds no session history entry. So frameloaded() is never called and the subtest can never finish. The written script also calls alert('pageshow'), which blocks under automation. Subtests t3 to t6 are commented out.

The file was checked off in #11269 (2018) when its harness ERROR was fixed, but it has timed out since.

Suggested fix:

• Rewrite the subtest to navigate the iframe, as 001.html does. 001.html passes 7/7 in Chrome.
• Or assert the post-whatwg/html#3946 behaviour: history.length stays 1 and no pageshow fires.
• Drop the alert() either way.

Found while triaging harness timeouts for a new engine; we can't pass this as written.