chromium/third_party/blink/web_tests/external/wpt/html/semantics/embedded-content/the-iframe-element/iframe-loading-lazy-in-script-disabled-iframe.html

<!DOCTYPE html>
<head>
<title>Iframes with loading='lazy' in script disabled iframe are not handled
       as 'lazy'</title>
<link rel="help" href="https://github.com/scott-little/lazyload">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>

<div style="height:1000vh;"></div>
<iframe id="iframe" sandbox="allow-same-origin"
        src="resources/iframe-loading-lazy-in-viewport.html">
</iframe>
<script>
promise_test(async t => {
  await new Promise(resolve => iframe.addEventListener("load", resolve));

  const inner_iframe = iframe.contentDocument.querySelector("iframe");

  assert_equals(inner_iframe.contentDocument.body.textContent.trim(), 'Subframe',
              "lazy-load iframe shouldn't be honored in script disabled iframe");
});
</script>