chromium/third_party/blink/web_tests/external/wpt/infrastructure/reftest/reftest.www.sub.html

<title>Tests that reftests obey the 'www' file-flag</title>
<link rel=match href=green.html>
<style>
:root {background-color:red}
</style>
<script>
if (location.hostname === "{{domains[www]}}") {
   document.documentElement.style.backgroundColor = "green";
}
</script>