title: jQuery UI :data selector does not return HTML5 data attributes
body: <p>Let say I have this piece of HTML :</p>
  
  <pre><code>&lt;div id="container"&gt;
     &lt;ul&gt;
         &lt;li&gt;&lt;a href="#" data-some-info="foo"&gt;Bar&lt;/a&gt;
         &lt;!-- repeating a few like the one --&gt;                          --&gt;
         &lt;!-- above for a while ...        --&gt;
     &lt;/uL&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>And I want to apply something to all the anchor elements with the data <code>some-info</code> when it is defined.</p>
  
  <p>I just want to understand why this behaviour (is it a bug?)</p>
  
  <pre><code>$("#container").find("a:data(some-info)").size();  // -&gt; 0
  $("#container").find("a").data("some-info");       // -&gt; "foo"
  $("#container").find("a:data(some-info)").size();  // -&gt; 1 (actual expected val)
  </code></pre>
  
  <p>Any ideas?</p>
  
  <p><strong>More Info</strong> : I'm using jQuery 1.9.0, and jQuery UI 1.9.2</p>
  
  <p>** <strong>Edit</strong> **</p>
  
  <p>I <em>know</em> about <code>$("#container").find("a[data-some-info]")</code>. This is not what I question here. If there is a <a href="http://api.jqueryui.com/data-selector/" rel="nofollow">data selector</a>, why does it behave this way?</p>