Description:
------------
The slashes (\) gets removed in some instances with invalid php code. In the below reproduce code, the \ gets removed.

The PHP Version isn't applicable, but I had to put 5.2.0 because if I set it to 'Irrelevant' I would get this error 'This category requires you to pick a PHP version.'

I understand that this is far fetched, but it should ATLEAST show up.

Reproduce code:
---------------
<?php
$string = '<?php
$a = 2;
\
$c = 5;
?>';

echo highlight_string($str, true);
?>

Expected result:
----------------
<?php
$a = 2;
\
$c = 5;
?>

Actual result:
--------------
<?php
$a = 2;

$c = 5;
?>