LayoutTests/imported/blink/http/tests/security/mixedContent/resources/frame-with-insecure-formSubmission.html

<form action="http://127.0.0.1:8080/security/resources/boring.html"
      method="post">
</form>
<script>
window.onload = function() {
    if (window.opener)
        window.opener.postMessage('done', '*');
};
</script>