Description:
------------
When calling parent::SELF_FIRST with recursiveDirectoryIterator fatal error

Reproduce code:
---------------
<?php
class DirectoryTreeIterator extends RecursiveDirectoryIterator{

public function __construct($path) {  parent::__construct(new RecursiveCachingIterator(
 new RecursiveDirectoryIterator($path,
 RecursiveDirectoryIterator::KEY_AS_FILENAME),
 CachingIterator::CALL_TOSTRING),
 parent::SELF_FIRST);
}

public function current() {
 $cur = "";
 for( $i = 0; $i < $this->getDepth(); $i++)
        {
        $cur .= $this->getSubIterator($i)->hasNext() ? " | " : " ";
        }
 $i = $this->SubIterator($i);
 return $cur . ($i->hasNext() ? " | - " : "/ - ").(string)$i;
}

} /*** end of class ***/

$obj = new DirectoryTreeIterator('albums');

Expected result:
----------------
directory list

Actual result:
--------------
Fatal error: Undefined class constant 'SELF_FIRST' in /www/web/test.php on line 9