<iframe src="javascript:..."> executes too soon, which is a symptom of HTMLIFrameElement::navigate_or_reload_child_browsing_context needing to perform navigation steps at the right time/on the right thread #24901
Description
WPT tests html/semantics/scripting-1/the-script-element/execution-timing/040, 080, 108, and 109 all create iframes with a javascript: url as their src, and in each case the javascript starts executing immediately, before the task that created the iframe finishes. According to these tests, which other browsers pass, that's incorrect behavior.