chromium/third_party/blink/web_tests/fast/frames/srcdoc/setting-src-does-nothing.html

<script>
if (window.testRunner) {
    testRunner.dumpAsText();
    testRunner.dumpChildFrames();
}
</script>
<p>This test ensures that setting the src attribute does not cause the document
inside the iframe to change.</p>
<iframe srcdoc="
  <script>
  window.frameElement.src = 'data:text/html,<script>alert(/FAIL/);<\/script>';
  </script>
  PASS
"></iframe>