title: iOS UiWebView / Page Visibility Api: "pageshow" event not firing
body: <p>I am trying to use the Page Visibility Api to detect when web content is being shown in iOS.  I have simple JS:</p>
  
  <blockquote>
  <pre><code>    window.addEventListener("pageshow", function(){
          alert("page shown");
      }, false);
  </code></pre>
  </blockquote>
  
  <p>The alert fires as expected in mobile safari when the tab is made active, or when safari is minimized and then re-shown.</p>
  
  <p>However if I host the web content in a UiWebView, the event is not firing.  Has anyone else encountered this issue?  If so any work around for this?</p>
  
  <p>Thanks...</p>