facebook/hhvm — pull request #1675 by cgcai (2014-01-30 19:05:51+00:00)
Title: Implemented hash_pbkdf2() function.

Defined in [PHP 5](http://www.php.net/manual/en/function.hash-pbkdf2.php) >= 5.5.0.

Moved passing tests to zend/good.