fieldset-content-percentage-size.html

<!DOCTYPE html>
<link rel="help" href="https://crbug.com/1140595">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<div style="height:100px;">
  <fieldset style="margin:0; padding:0; border:none;">
    <div id="inner" style="height:59%;"></div>
  </fieldset>
</div>
<script>
test(() => {
  let innerDiv = document.querySelector('#inner');
  assert_equals(innerDiv.clientHeight, 0);
}, 'A percentage height for an element in an auto-height fieldset should be ignored');
</script>

chromium/third_party/blink/web_tests/external/wpt/html/rendering/non-replaced-elements/the-fieldset-and-legend-elements/fieldset-content-percentage-size.html