title: Using polyfill for formData and IE still throwing error: Object doesn't support this action
body: <p>I am using a npm package called formdata-pollyfill which is suppose to fix the issue when using IE and <code>FormData</code> method set. Yet when I call <code>.set</code> it throws the <code>Object doesn't support this action</code> error.</p>
  
  <pre><code>import formData from 'formdata-polyfill'
  
  let data = new formData(form);
  data.set('foo', 'bar') // --&gt; Object doesn't support this action
  </code></pre>