What is the issue with the HTML Standard?

https://github.com/web-platform-tests/wpt/blob/master/dom/nodes/insertion-removing-steps/script-does-not-run-on-child-removal.window.js

Tests that child removal does not remove script, which gecko chromium and webkit all follow.

But from what I understand the last assertion fails when following spec as script execution is triggered from the children changed steps / post connection

whatwg/dom#1288 relates to this