Description:
------------
Method calls fail on DOM document objects passed as session variables.  This happens whether you pass the DOM document object itself or a reference to the object as a session variable.  If you serialize and unserialize an object reference to a DOM document object without passing it as a session variable, it works fine:

<?php

  /**
   * This test shows that a reference to a DOM object can be
   * serialized and unserialized and still be used.
   */
$xml = "<?xml version='1.0' ?><foo><bar>Hoot!</bar></foo>";
$foo =& domxml_open_mem($xml);
$foo = unserialize(serialize($foo));
print $foo->dump_mem();

?>


Reproduce code:
---------------
<?php

session_start();

/**
 * This code tests method calls on a reference to a DOM object that
 * has been passed as a session variable.
 */

if (session_is_registered('foo')) {
    $_SESSION['foo']->dump_mem();
    session_unregister('foo');
 } else {
    print "Creating reference to new DOM object as a session variable...";
    session_register('foo');
    $xml = "<?xml version='1.0' ?><foo><bar>Hoot!</bar></foo>";
    $_SESSION['foo'] =& domxml_open_mem($xml);
 }

?>

<?php

session_start();

/**
 * This code tests method calls on a DOM object that has been passed
 * as a session variable.
 */

if (session_is_registered('foo')) {
    $_SESSION['foo']->dump_mem();
    session_unregister('foo');
 } else {
    print "Creating new DOM object as a session variable...";
    session_register('foo');
    $xml = "<?xml version='1.0' ?><foo><bar>Hoot!</bar></foo>";
    $_SESSION['foo'] = domxml_open_mem($xml);
 }

?>


Expected result:
----------------
Both of these scripts should print the original xml source.


Actual result:
--------------
Both fail with "Warning: dump_mem(): Underlying object missing or of invalid type" followed by "Warning: dump_mem():  Cannot fetch DOM object" error.