title: JavaScript dialogs alert(), confirm() and prompt() in cross origin iframe does not work any longer
body: <p>Apps script web app works in <code>&lt;iframe&gt;</code>. It seems Chrome is no longer supporting <code>alert()</code>, <code>confirm()</code>, Promote these functions on the web app.</p>
  <p>Any workaround to this?</p>
  <ul>
  <li>Chrome Version 92.0.4515.107 (Official Build) (64-bit) -- does not work</li>
  <li>Edge Version 91.0.864.71 (Official build) (64-bit) -- works</li>
  </ul>
  <p>Tried replacing <code>alert()</code> with <code>window.alert()</code>, but still does not work.</p>
  <blockquote>
  <p>exec:1 A different origin subframe tried to create a JavaScript dialog. This is no longer allowed and was blocked. See <a href="https://www.chromestatus.com/feature/5148698084376576" rel="noreferrer">https://www.chromestatus.com/feature/5148698084376576</a> for more details.</p>
  </blockquote>