title: Polymer : Uncaught (in promise) ReferenceError: IntlMessageFormat is not defined
body: <p>I am using Plunker for an <code>i18n</code> demo with Polymer, but I am getting an error:</p>
  
  <pre><code>Uncaught (in promise) ReferenceError: IntlMessageFormat is not defined
  </code></pre>
  
  <p><a href="https://plnkr.co/edit/JyjExwp5pjCmPqgErCtk?p=preview" rel="nofollow noreferrer">Plunker for i18n</a></p>
  
  <p>The default is English, which is also not displaying because of the above error. I'd like it to show:</p>
  
  <pre><code>My name is Batman.
  </code></pre>
  
  <p>And on changing the dropdown from <code>English</code> to <code>France</code>, the text should be changed to:</p>
  
  <pre><code>Je m'apelle Batman.
  </code></pre>
  
  <p>This code works fine on my local system, but not Plunker. What am I missing?</p>