<!DOCTYPE html>
<meta charset="utf-8">
<title>Check for crash at step #12 of HTML Constructors</title>
<meta name='author' href='mailto:masonf@chromium.org'>
<link rel='help' href='https://html.spec.whatwg.org/multipage/dom.html#html-element-constructors'>
<link rel='help' href='https://crbug.com/1197894'>

<uh-oh></uh-oh>

<script type="module">
  Reflect.preventExtensions(document.querySelector('uh-oh'));
  customElements.define('uh-oh', class extends HTMLElement {});
</script>

This test passes if it does not crash.
