BasicAuthTestTrait::basicAuthPostForm() does not work

Problem/Motivation

Drupal\Tests\basic_auth\Traits\BasicAuthTestTrait::basicAuthPostForm() has the following code:

protected function basicAuthPostForm($path, $edit, $submit, $username, $password, array $options = [], $form_html_id = NULL, $extra_post = NULL) {
  return $this->drupalPostForm($path, $edit, $submit, $options, $this->getBasicAuthHeaders($username, $password), $form_html_id, $extra_post);
}

However the signature of drupalPostForm() is:

protected function drupalPostForm($path, $edit, $submit, array $options = [], $form_html_id = NULL) {

ie. the Authorization header is passed as the $form_html_id element, which will not work.

Steps to reproduce

Proposed resolution

The method is never called in core or contrib (no results at http://grep.xnddx.ru/search?text=basicAuthPostForm&filename= ) so I suggest just removing it.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet