Description:
------------
When a copyright character (ascii 169) is present in a string that is added as a text node to the DOM structure, the element is always empty.  The correct behavior is to encode the character as "©".

Reproduce code:
---------------
<?php
$doc = new DOMDocument('1.0');
$t = $doc->appendChild($doc->createElement('test'));
$t->appendChild($doc->createTextNode('&' . chr(169) . '<'));

header('Content-type: text/xml');
echo $doc->saveXML();
?>


Expected result:
----------------
<?xml version="1.0"?>
<test>&amp;&copy;&lt;</test>

Actual result:
--------------
<?xml version="1.0"?>
<test></test>