LayoutTests/http/tests/preload/resources/dummy-preloads-subresource.css.php

<?php
header("Link: <../resources/dummy.js>; rel=preload; as=script", false);
header("Link: <../resources/dummy.js?media>; rel=preload; as=script; media=all", false);
?>
/* This is just a dummy, empty CSS file */