title: input tag inside anchor tag with target _blank fires twice
body: <p>In a html page, I added the following code</p>
  
  <pre><code>&lt;a href="http://www.google.com" target="_blank"&gt;&lt;span&gt;&lt;input type="button" value="google" /&gt;&lt;/span&gt;&lt;/a&gt;
  </code></pre>
  
  <p>To achieve image button with sliding door technique, I happens to mark up like this.</p>
  
  <p>Now when I click the button, google.com opens in two tabs in Firefox.</p>
  
  <p>IE didn't respond at all.</p>