title: responsive images srcset not working
body: <p>I've been trying to implement the new srcset approach to responsive images, using the following HTML</p>
  
  <pre><code>        &lt;img class="swapImages"
          srcset="assets/images/content/large.jpg 1200w,
                  assets/images/content/medium.jpg 800w,
                  assets/images/content/small.jpg 400w"
          sizes="100vw"
          src="assets/images/content/small.jpg"
          alt="responsive image"&gt;
  </code></pre>
  
  <p>Im using chrome 40 and all I get is the largest image, resizing my browser, clearing the cache does nothing.</p>
  
  <p>I read somewhere I had to polyfill, so I used the picturefill plugin, although chrome should support it.....still doesn't work.</p>
  
  <p>I put together a demo page for it:
  <a href="http://www.darrencousins.com/lab/resp-img-srcset/">http://www.darrencousins.com/lab/resp-img-srcset/</a></p>
  
  <p>What am I doing wrong/not getting?</p>
  
  <p>Any help is massively appreciated.</p>