Language: PHP
Label: safe
CWE: CWE-79 \u2014 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Code:
            $stack[count($stack)-1]->children[] = $node;
            if ($token instanceof HTMLPurifier_Token_Start) {
                $stack[] = $node;
            }
        }
        //assert(count($stack) == 1);
        return $stack[0];
    }