title: WebDriver find Element not containing attribute
body: <p>I have following HTML</p>
  
  <pre><code>&lt;button class="x-btn-text " style="position: relative; width: 69px;" type="button" tabindex="0" aria-disabled="false"&gt;OK&lt;/button&gt;
  &lt;button class="x-btn-text" style="position: relative; width: 69px;" type="button" tabindex="0"&gt;OK&lt;/button&gt;
  </code></pre>
  
  <p>The first button is disabled and the second button is enabled, since I want to click on the enabled button. Is there a way I could find the element, that doesn't have attribute <code>aria-disabled</code>?</p>