title: Writing cssselector expression for webDriver using attribute matching
body: <p>I am a newbie to css, html, etc and thus cssselectors. I have been messing around with selenium webdriver and am trying to .click() the following button:</p>
  
  <pre><code>&lt;button title="" class="btn addWidgButt bt-block" href="" role="button" type="button"     context="UNIQUE_THING"&gt;
  &lt;span class="btn-text"&gt;UNIQUE THING&lt;/span&gt;&lt;/button&gt;
  </code></pre>
  
  <p>According to <a href="http://www.w3.org/TR/css3-selectors/#selectors" rel="nofollow">http://www.w3.org/TR/css3-selectors/#selectors</a> shouldn't the following selector work? (Rule is E[foo="bar"] for element E</p>
  
  <pre><code>By.cssSelector("button title[context=UNIQUE_THING]")
  By.cssSelector("btn.addWidgButt.bt-block[context=UNIQUE_THING]")
  By.cssSelector("span[btn-text=UNIQUE THING]")
  </code></pre>
  
  <p>I think the last one is my best bet, as span is an element and btn-text is an attribute value. Any help is appreciated, thanks.</p>