Description:
------------
When you register a shutdown function with register_shutdown_function, and using trigger_error to give a error to the user, the function registered by register_shutdown_function isn't called.

Reproduce code:
---------------
<?php
class error
{
function shutdown()
{
print "blabla";
}
}
$error = new error();
register_shutdown_function(array($error, 'shutdown'));
trigger_Error('Error here', E_USER_ERROR);
?>

Expected result:
----------------
Fatal error: Error here in /var/www/error.php on line 11
blabla


Actual result:
--------------
Fatal error: Error here in /var/www/error.php on line 11