Wordpress: Detect Visitors Browser and output in body class

/**
 * Detect Visitors Browser
 *
 **/
add_filter('body_class','myfunction_browser_body_class');
function myfunction_browser_body_class($classes) {
	global $is_lynx, $is_gecko, $is_IE, $is_opera, $is_NS4, $is_safari, $is_chrome, $is_iphone;
 
	if($is_lynx) $classes[] = 'lynx';
	elseif($is_gecko) $classes[] = 'gecko';
	elseif($is_opera) $classes[] = 'opera';
	elseif($is_NS4) $classes[] = 'ns4';
	elseif($is_safari) $classes[] = 'safari';
	elseif($is_chrome) $classes[] = 'chrome';
	elseif($is_IE) $classes[] = 'ie';
	else $classes[] = 'unknown';
 
	if($is_iphone) $classes[] = 'iphone';
	return $classes;
}