chromium/third_party/blink/web_tests/fast/history/resources/form-with-onclick-submit.html

<!DOCTYPE html>
<html>
<body>
Frame 1

<script>document.write('<form name="testform" method="post" action="redirect-target.html#' + (history.length + 1) + '">');</script>
  <input type="button" id="submit-button" value="Submit" onClick="document.forms.testform.submit();">
</form>

</body>
</html>