WP_Widget_Custom_HTML::_register_one

	public function _register_one( $number = -1 ) {
		parent::_register_one( $number );
		if ( $this->registered ) {
			return;
		}
		$this->registered = true;

		wp_add_inline_script( 'custom-html-widgets', sprintf( 'wp.customHtmlWidgets.idBases.push( %s );', wp_json_encode( $this->id_base ) ) );

		// Note that the widgets component in the customizer will also do
		// the 'admin_print_scripts-widgets.php' action in WP_Customize_Widgets::print_scripts().
		add_action( 'admin_print_scripts-widgets.php', array( $this, 'enqueue_admin_scripts' ) );

		// Note that the widgets component in the customizer will also do
		// the 'admin_footer-widgets.php' action in WP_Customize_Widgets::print_footer_scripts().
		add_action( 'admin_footer-widgets.php', array( 'WP_Widget_Custom_HTML', 'render_control_template_scripts' ) );

		// Note this action is used to ensure the help text is added to the end.
		add_action( 'admin_head-widgets.php', array( 'WP_Widget_Custom_HTML', 'add_help_text' ) );
	}