title: HTML 5 filesystem access Type Error
body: <p>I'm working on a webapp and I'm trying to access directories using the filesystem API. I need to request a quota from the user before accessing the directories according to specification. I should do something like this:</p>
  
  <pre><code>...
  navigator.webkitPersistentStorage.requestQuota(PERSISTENT, 1024*1024, 
  function(gB){
     window.requestFileSystem(PERSISTENT, gB, onInitFs, errorHandler);
  }, function(e){
     console.log('Error', e);
  })
  ...
  </code></pre>
  
  <p>Everytime I do this I get a <code>**TypeError: Type error**</code> message. Please what am I doing wrong? Thanks in advance.
  <br>NB: onInitFs and errorHandler have been defined I just didn't include the code here.</p>