title: Do all search bots use escaped fragment?
body: <p>I've built an Angular SPA. Some of my <code>head</code> code looks like this:</p>
  
  <pre><code>&lt;!--title--&gt;
  &lt;title ng-bind="$root.title"&gt;&lt;/title&gt;
  
  &lt;!--web--&gt;
  &lt;meta name="application-name" content="{{$root.site.name}}"&gt;
  &lt;meta name="description" content="{{$root.page.description}}"&gt;
  
  &lt;!--facebook--&gt;
  &lt;meta property="og:type" content="website"&gt;
  &lt;meta property="og:title" content="{{$root.page.title}}"&gt;
  &lt;meta property="og:url" content="{{$root.site.url}}"&gt;
  &lt;meta property="og:image" content="{{$root.site.url}}/framework/img/brand/facebook.jpg"&gt;
  &lt;meta property="og:description" content="{{$root.page.description}}"&gt;
  
  &lt;!--twitter--&gt;
  &lt;meta name="twitter:card" content="summary"&gt;
  &lt;meta name="twitter:title" content="{{$root.page.title}}"&gt;
  &lt;meta name="twitter:url" content="{{$root.site.url}}"&gt;
  &lt;meta name="twitter:image" content="{{$root.site.url}}/framework/img/brand/social.jpg"&gt;
  &lt;meta name="twitter:description" content="{{$root.page.description}}"&gt;
  
  &lt;!--routing--&gt;
  &lt;base href="/"&gt;
  &lt;meta name="fragment" content="!"&gt;
  </code></pre>
  
  <p>For the purpose of SEO I've set my app to recognise requests with the escaped fragment <code>?_escaped_fragment_=</code>. When these requests come through, it serves a prerendered version of the page.</p>
  
  <p>Does every search bot use the escaped fragment? For example, if I post a link to a page of my SPA on Facebook, will it fetch the prerendered version of the page, or the unrendered version?</p>
  
  <p>Facebook should hopefully go to the page, see the fragment meta tag and understand it's an ajax application, then revisit the page with the escaped fragment to receive prerendered content.</p>