title: execcommand("SaveAs",null,"file.csv") is not working in IE8
body: <pre><code>var doc = w.document;
  doc.open('application/CSV','replace');
  doc.charset = "utf-8";
  doc.write("all,hello");
  doc.close();
  
  if(doc.execCommand("SaveAs",null,"file.csv")) {
      window.alert("saved ");
  }else {
      window.alert("cannot be saved");
  }
  </code></pre>
  
  <p>not working in IE 8 </p>
  
  <p>but woks in IE 6</p>
  
  <p>what is the problem ? it is alerting "cannot be saved"</p>
  
  <p>help me !!! advance thanks </p>