title: window.open not working in chrome extension popup
body: <p>i want to create a button on a popup page that redirect to google search page when clicked
  so i used window.open
  this is the html</p>
  
  <pre><code>&lt;li&gt; 
      &lt;input type="image" src="http://www.google.com/s2/favicons?domain=www.google.com" onClick="google()"&gt;
  &lt;/li&gt;
  </code></pre>
  
  <p>and the javascript </p>
  
  <pre><code>function google(){ 
      window.open("http://www.google.com/search?q="+document.search.query.value);
  }
  </code></pre>
  
  <p>this works fine when i preview the code in chrome window but in the extension popup page the button doesn't do anything, why?</p>