Provide some way to disable the core_formchangechecker for a given form

This test script demonstrates the problem. If you run it, you will get a JavaScript error. The two comments indicate two ways to make the error go away. If you are doing clever Ajax things then you need the new disable_form_change_checker way of doing it. <?php require_once('config.php'); require_once($CFG->libdir . '/formslib.php');   $PAGE->set_context(context_system::instance()); $PAGE->set_url('/test.php');   class myform extends moodleform { protected function definition() { // Uncomment the following line to make the JavaScript error go away. // $this->_form->disable_form_change_checker(); $this->add_action_buttons(); }   public function render() { ob_start(); $this->display(); return ob_get_clean(); } }   $mform = new myform();   echo $OUTPUT->header(); // For some reason, render a form without outputting it. The JavaScript error // will also go away if you add echo to the start of the next line. $mform->render(); echo $OUTPUT->footer();