Fix: Crashed at HHVM.

This moves at PHP 5.4-5.6 but crashes HHVM.
```php
<?php
class Ca {
    public function m() {
        echo 'A';
    }
}
class Cb extends Ca {
    public function m() {
        echo 'B1';
        //parent::m();
        (new \ReflectionClass('Ca'))->getMethod('m')->invoke($this);
        echo 'B2';
    }
}
(new Cb)->m();
echo "\n";
```
So we use call_user_func_array and parent::.