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chromium/third_party/blink/web_tests/fast/forms/text/text-placeholder-inserthtml.html 

<!DOCTYPE html>
<body>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit <input placeholder="Lorem ipsum dolor sit amet, consectetur adipiscing elit">Lorem ipsum dolor sit amet, consectetur adipiscing elit</p>
<script>
if (window.testRunner)
  testRunner.waitUntilDone();
document.querySelector('input').focus();
requestAnimationFrame(() => {
  requestAnimationFrame(() => {
    document.execCommand("InsertHTML", false, "<a href='#'>link</a>");
    document.execCommand("SelectAll");
    document.execCommand("InsertText", false, "");
    requestAnimationFrame(testRunner.notifyDone.bind(testRunner));
  });
});
</script>
</body>