Issue #2030165 by Berdir, tim.plunkett, vijaycs85, tkuldeep17 | rteijeiro: Convert form_test_* functions to classes.
Issue #2163209 by andrewmacpherson, mgifford | Charles Belov: Add alternate text to file icon.
Issue #2301591 by joshi.rohit100: Remove drupal_rebuild_form() as it is deprecated.
Issue #2297487 by er.pushpinderrana, marcingy: Remove the check_plain function.
Issue #2301953 by er.pushpinderrana | scor: Fixed Update 'element-invisible' and 'element-hidden' to valid Drupal 8 CSS classes.