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chromium/third_party/blink/web_tests/external/wpt/html/infrastructure/safe-passing-of-structured-data/resources/post-parent-type-error.html 

<!DOCTYPE html>
<meta charset="utf-8">
<title>Helper that posts its parent a TypeError</title>

<script>
window.doIt = () => {
  parent.postMessage(new TypeError("!!"), "*");
};
</script>