title: Polyfill for CSS `background-position-x/y`? jquery-backgroundfix not working
body: <p>Expanding on <a href="https://stackoverflow.com/questions/9653685/is-background-position-x-background-position-y-a-standard-w3c-css-property">Is background-position-x (background-position-y) a standard W3C CSS property?</a> -- is there a polyfill for CSS <code>background-position-x/y</code>?</p>
  
  <p>I found <a href="https://github.com/liuxuanzy/jquery-backgroundfix" rel="nofollow noreferrer">https://github.com/liuxuanzy/jquery-backgroundfix</a> but I'm having some trouble making it work:</p>
  
  <ul>
  <li>Pure JS: <a href="http://jsbin.com/ripegiqose/1/edit" rel="nofollow noreferrer">http://jsbin.com/ripegiqose/1/edit</a></li>
  <li>Ruby on Rails (Bower + <a href="http://rails-assets.org/" rel="nofollow noreferrer">http://rails-assets.org/</a>): <a href="http://runnable.com/VL0J_279Y69u6gxa/rails-jquery-backgroundfix" rel="nofollow noreferrer">http://runnable.com/VL0J_279Y69u6gxa/rails-jquery-backgroundfix</a></li>
  </ul>