chromium/third_party/blink/web_tests/svg/text/text-decoration-thickness-in-iframe.html

<!DOCTYPE html>
<title>Underline thickness of a pair of lines should be identical</title>
<body style="overflow:hidden">
<div id="transformed-div" style="transform: scale(8); transform-origin: 0 0 0;">
  <svg height="18" width="200">
    <text font-size="8" y="10" style="
        text-decoration: underline;
    ">Underline text</text>
  </svg>
  <div></div>
</div>

<div id="transformed-div2" style="transform: scale(3); transform-origin: 0 0 0; margin-top:400px">
  <svg height="18" width="200">
    <text font-size="6" y="10" style="
        text-decoration: underline;
    ">Underline text</text>
  </svg>
  <div></div>
</div>

<script>
let root = document.querySelector("#transformed-div");
let iframe = document.createElement('iframe');
root.querySelector('div').appendChild(iframe);
iframe.height = 24;
iframe.setAttribute("srcdoc",
  `<html><body style="margin:0">${root.querySelector('svg').outerHTML}</body></html>`);

root = document.querySelector("#transformed-div2");
iframe = document.createElement('iframe');
root.querySelector('div').appendChild(iframe);
iframe.height = 100;
iframe.setAttribute("srcdoc",
  `<html><body style="margin:0">${root.querySelector('svg').outerHTML}</body></html>`);
</script>
</body>