Codebase Browser
chromium
Go to App

chromium/third_party/blink/web_tests/external/wpt/domparsing/resources/domparser-iframe-base.html 

<!DOCTYPE html>
<meta charset="utf-8">
<title>An iframe that does DOMParser stuff with base</title>
<base href="/fake/base-from-iframe">

<script src="/domparsing/resources/domparser-iframe.js"></script>