Adds the form.requestSubmit() function, which requests form submission. It includes interactive constraint validation, dispatches a 'submit' event, and takes a reference to the submitter button.
https://github.com/whatwg/html/issues/4187 requestSubmit() exposes what click() implementation of built-in submit buttons do. It would be helpful to make developer's own submit buttons. form.submit() was not enough because it doesn't trigger interactive constraint validation, doesn't dispatch 'submit' event, and doesn't make a form data entry for the submit button.
Docs: https://html.spec.whatwg.org/C/forms.html#dom-form-requestsubmit-dev
Explainers: https://html.spec.whatwg.org/C/forms.html#dom-form-requestsubmit-dev