title: G plus share button not W3C valid
body: <p>How to make this part of HTML valid HTML5?</p>
  
  <pre><code>&lt;div class="addthis_toolbox addthis_default_style addthis_32x32_style"&gt;
  &lt;a class="addthis_button_google_plusone" g:plusone:annotation="none"&gt;&lt;/a&gt;
  .
  .
  &lt;/div&gt;
  &lt;script type="text/javascript" src="http://s7.addthis.com/js/300
  /addthis_widget.js#pubid=ra-xxxxx"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>The result of the W3C-validator is this:</p>
  
  <blockquote>
    <p>Warning Line xx, Column xx: Attribute g:plusone:annotation is not serializable as XML 1.0.</p>
  </blockquote>
  
  <p></p>
  
  <blockquote>
    <p>Error Line xx, Column xx: Attribute g:plusone:annotation not allowed on element a at this point.</p>
  </blockquote>
  
  <pre><code>&lt;a class="addthis_button_google_plusone" g:plusone:annotation="none"&gt;&lt;/a&gt;
  </code></pre>
  
  <p>Thanks,</p>