Test checks the prolog generation with dynamic attributes

>>>>templates/test.tpl
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<!-- Display the prolog -->
<opt:root>
foo
<opt:prolog parse:encoding="$fff" />
foo
</opt:root>

>>>>expected.txt
OUTPUT

>>>>data.php
$view->assign('fff', 'UTF-8');

>>>>result.txt
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
foo
foo