Feature detect ES modules: both static import and dynamic import()

## feature_detect_es_modules.js
<!--
Complete feature detection for ES modules. Covers:

1. Static import: import * from './foo.js';
2. Dynamic import(): import('./foo.js').then(module => {...});

Demo: http://jsbin.com/tilisaledu/1/edit?html,output

Thanks to @_gsathya, @kevincennis, @rauschma, @malyw for the help.
-->

<body></body>

<!-- Remember: static modules have a fallback! -->
<script type="module">
  console.log('This browser supports <script type="module">');
</script>
<script nomodule>
  console.log('This browser DOES NOT support <script type="module">');
</script>

<script>
// Feature detect static imports.
function supportsStaticImport() {
  const script = document.createElement('script');
  return 'noModule' in script;
}

// Feature detect dynamic import().
function supportsDynamicImport() {
  try {
    new Function('import("")');
    return true;
  } catch (err) {
    return false;
  }
}

// Usage.
let el = document.createElement('pre');
el.textContent = `
  Supports ES module static import: ${supportsStaticImport()}
  Supports dynamic ES module import(): ${supportsDynamicImport()}
`
document.body.appendChild(el);
</script>