Stop ESC key propagation when closing a submenu

[mrwweb]

For cases where a submenu is inside another togglable element, the ESC key should close an open submenu but not close the containing element. Add this so that ESC only closes a parent element if no submenus are open:

function closeOnEscKey( e ) {
	if ( 27 === e.keyCode ) {
		// we're in a submenu item
		if ( null !== e.target.closest( 'ul[aria-hidden="false"]' ) ) {
			currentMenuItem.focus();
			toggleSubmenu( currentMenuItem );
			e.stopPropagation(); // ADDED!
		// we're on a parent item
		} else if ( 'true' === e.target.getAttribute( 'aria-expanded' ) ) {
			toggleSubmenu( currentMenuItem );
			e.stopPropagation(); // ADDED!
		}
	}
}