title: Find prev() tags with several selectors
body: <p>Let's face this situation:</p>
  
  <pre><code>&lt;ul&gt;
    &lt;li&gt;data&lt;/li&gt;
    &lt;li class="selector"&gt;data2&lt;/li&gt;
    &lt;li class="selector2"&gt;data3&lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>What i'm trying to do is match <code>li</code>s that either have <code>selector</code> class or have class attribute <code>undefined</code>, something like this:</p>
  
  <pre><code>jQuery(function($) {
    $('.selector2').prevAll('li.selector OR li[class==""]');
  });
  </code></pre>
  
  <p>So if I'm running <code>prevAll()</code> on the <code>.selector2</code>, it should return 2 list items. If i run it on <code>.selector</code>, it should return the first list item.</p>
  
  <p>So is there a way to replace that OR ... ?</p>
  
  <p><em>PS: xpath may work for me too as i'm developing for modern browsers</em></p>