- https://html.spec.whatwg.org/multipage/webappapis.html#processing-model-9 - [Perform a microtask checkpoint](https://html.spec.whatwg.org/multipage/webappapis.html#perform-a-microtask-checkpoint) - [Microtask queue](https://html.spec.whatwg.org/multipage/webappapis.html#microtask-queue) This blocks #4282 #1980