title: Embedding Facebook posts via iframe not working
body: <p>I'm attempting to embed a facebook post onto a website. I took Facebook's most basic example and plugged it into the html. On the page I see a big empty space, but no embed post. If I visit Chrome or Safari this looks perfectly fine. I'm using Firefox 47. What's interesting is that in Firefox when I visit the iframe tag I see the following generated html.</p>
  
  <p>Generated html for embedded post:</p>
  
  <pre><code>&lt;iframe style="border: none; overflow: hidden;" src="https://www.facebook.com/plugins/post.php?href=https%3A%2F%2Fwww.facebook.com%2F20531316728%2Fposts%2F10154009990506729%2F&amp;amp;width=500&amp;amp;show_text=true&amp;amp;height=290&amp;amp;appId" width="500" height="290" frameborder="0" scrolling="no"&gt;
  &lt;/iframe&gt;
  </code></pre>
  
  <p>Code inside <code>iframe</code>:</p>
  
  <pre><code>&lt;html&gt;
    &lt;head&gt;&lt;/head&gt;
    &lt;body&gt;&lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>What's wrong and how do I fix this?</p>