vialatina on "Flutter Plugin Warning"

Good Night. I've a problem with this code, and i can't fix it. The site looks like this: http://www.revistavialatina.com/?p=2859 . Thanks for your help.

function dircopy($src_dir, $dst_dir, $verbose = false, $use_cached_dir_trees = false)
{
static $cached_src_dir;
static $src_tree;
static $dst_tree;
$num = 0;

if (($slash = substr($src_dir, -1)) == "\\" || $slash == "/") $src_dir = substr($src_dir, 0, strlen($src_dir) - 1);
if (($slash = substr($dst_dir, -1)) == "\\" || $slash == "/") $dst_dir = substr($dst_dir, 0, strlen($dst_dir) - 1);

if (!$use_cached_dir_trees || !isset($src_tree) || $cached_src_dir != $src_dir)
{
$src_tree = get_dir_tree($src_dir);
$cached_src_dir = $src_dir;
$src_changed = true;
}