function assertAfterInsertionEquals(expected, input) {
  const sanitizer = new Builder().allowFormTag().build();
  input = SafeHtml.unwrap(sanitizer.sanitize(input));
  const div = document.createElement('div');
  document.body.appendChild(div);
  div.innerHTML = input;
  testingDom.assertHtmlMatches(
      expected, div.innerHTML, true /* opt_strictAttributes */);
  div.parentNode.removeChild(div);
}
Sanitize content, let the browser apply its own HTML tree correction by
attaching the content to the document, and then assert it matches the
expected value.
@param {string} expected
@param {string} input