Description:
------------
dom_import_simplexml() as described in the following document:
http://www.zend.com/php5/articles/php5-xmlphp.php#Heading16,
is meant to return a DOMDocument, but instead returns a DOMElement.

Reproduce code:
---------------
<?php
$xml_file = "moo.xml";
$schema_file = "boo.xsd";

$src = simplexml_load_file($xml_file);            
$dom = dom_import_simplexml($src);               
$dom->schemaValidate($schema_file);
?>


Expected result:
----------------
A validation message based on the XML schema file and the XML instance file.

Actual result:
--------------
Output: Fatal error: Call to undefined method DOMElement::schemaValidate()