<!doctype html>
<html>
<head>
<title>customElements#polyfillWrapFlushCallback</title>
<script>
  (window.customElements = window.customElements || {}).forcePolyfill = true;
</script>
<script src="../../../node_modules/es6-promise/dist/es6-promise.auto.min.js"></script>
<script src="../../../node_modules/wct-browser-legacy/browser.js"></script>
<script src="../../../custom-elements.min.js"></script>
<script>
/**
 * @license
 * Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
 * This code 