title: window.requestFileSystem not working
body: <p>I am trying on Firefox,IE 9,Chrome and Opera the code below ,but the onInitFs(fs) function doesn't get called.if I  add '()' to onInitFs in the window.requestFileSystem(window.PERSISTENT, 1024*1024, onInitFs, errorHandler) that function get called but fs is null ?
  Does anybody know how to solve this problem?I try on windows 7.I'll appreciate very much your help.</p>
  
  <pre><code>&lt;!DOCTYPE HTML&gt;
  `&lt;html&gt;
      &lt;head&gt;  
      &lt;script&gt;
          function errorHandler(e){
              alert("errorrrr");
          }
          function onInitFs(fs){
          alert("onInitFs");
          }
          function readClick(){
                   if (window.webkitRequestFileSystem) {
                       window.webkitRequestFileSystem(window.PERSISTENT, 1024*1024,onInitFs,errorHandler);
                  } 
                   else {
                      window.requestFileSystem(window.PERSISTENT, 1024*1024, onInitFs, errorHandler);
                  }
  
              alert("read finishsssss");
          }
          &lt;/script&gt;
      &lt;/head&gt;
  &lt;body&gt;
  &lt;input type="button" value="Read dir" onclick="readClick()"&gt;
      &lt;ul id="filelist"&gt;&lt;/ul&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>