chromium/third_party/blink/web_tests/external/wpt/fetch/content-length/content-length.html

<!DOCTYPE html>
<!-- CAUTION: if updating this test also update the expected content-length in the .headers file -->
<title>Content-Length Test</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
setup({ single_test: true });
onload = function() {
  assert_equals(document.body.textContent, "PASS");
  done();
}
</script>
<body>PASS
but FAIL if this is in the body.