title: CSS-filter: Invert does not work in mozilla
body: <p>Title describes the problem.
  Here is my code </p>
  
  <pre><code>.img { 
      -webkit-filter: invert(100%);
      -o-filter: invert(100%);
      -moz-filter: invert(100%);
      -ms-filter: invert(100%);
      filter: invert(100%);
  }
  </code></pre>
  
  <p>Works fine fine in chrome, but firefox does not display inverted colors.</p>
  
  <p><strong>EDIT</strong>
  Browser versions: Firefox 29.0.1 &amp;&amp; Chrome  36.0.1985.125</p>