title: .addClass() doesn't update style in Chrome, but manually adding the class works
body: <p>This works on FF, but not Chrome and Safari.</p>
  
  <p>On <a href="http://iedm.com/collections/kaleidoscope-glasses/products/kaleidoscope-diffraction-goggles" rel="nofollow">product pages</a>, I'm adding class "adding-to-cart" onclick, and then removing the class after the ajax add to cart call finishes.</p>
  
  <p>The JS is properly adding the class. You can see by highlighting the element in developer tools before you click, then see the class is being properly added and then removed.</p>
  
  <p>It's not a CSS specificity issue, because if you edit the html in developer tools and add the class, it changes the style. I actually went extra specific, just to make sure.</p>
  
  <p>CSS:</p>
  
  <pre><code>#product-add-to-cart.adding-to-cart,
  #product-add-to-cart.adding-to-cart:active,
  #product-add-to-cart.adding-to-cart:focus {
    background: #ccc !important;
  }
  </code></pre>
  
  <p>Why does this work on FF, but not other browsers? Have you seen something like this before?</p>