title: Using attr(data-icon) property to display unicode before element
body: <p>Lets demonstrate an example with simple HTML code like this:</p>
  
  <pre><code>&lt;div data-icon="\25B6"&gt;Title&lt;/div&gt;
  </code></pre>
  
  <p>I would like this element to have an prefix icon set by it's data attribute (data-icon) so I set CSS file like this:</p>
  
  <pre><code>div:before {
      content: attr(data-icon);
  }
  </code></pre>
  
  <p>My desired output of this example would look like this:</p>
  
  <pre><code>▶Title
  </code></pre>
  
  <p>Instead of desired output all I can get is this:</p>
  
  <pre><code>\25B6Title
  </code></pre>
  
  <p>So my question is: what am I doing wrong / what am I missing? </p>
  
  <p>JSFiddle example: <a href="http://jsfiddle.net/Lqgr9zv6/" rel="noreferrer">http://jsfiddle.net/Lqgr9zv6/</a></p>