ElementInternals reportValidity() should focus the validation anchor element

[zcorpan]

What is the issue with the HTML Standard?

See web-platform-tests/wpt#47934 and demo https://software.hixie.ch/utilities/js/live-dom-viewer/saved/13058

The spec for report validity steps says

If report is true, then report the problems with the constraints of this element to the user. When reporting the problem with the constraints to the user, the user agent may run the focusing steps for element, and may change the scrolling position of the document, or perform some other action that brings element to the user's attention. User agents may report more than one constraint violation, if element suffers from multiple problems at once.

element is the custom element, not the validation anchor element set up in https://html.spec.whatwg.org/#dom-elementinternals-setvalidity

It seems browsers focus the validation anchor element instead of element.