Validation processing occurs when not using AJAX comments

The AjaxCommentsForm overrides the normal comment form and in almost all the overridden methods, it checks to make sure AJAX comments are actually enabled on that comment before proceeding with the special logic.

One spot is missing this though: validateForm(). This can end up generating errors for non-AJAX comments because the tempstore is looking for a form element (form_html_id) to be there that would only exist if the specialized code was run when originally building the form.