title: IE9 array does not support indexOf
body: <p>Based on <a href="http://ie.microsoft.com/testdrive/HTML5/ECMAScript5Array/Default.html" rel="noreferrer">http://ie.microsoft.com/testdrive/HTML5/ECMAScript5Array/Default.html</a>, I thought IE9 supports indexOf in array but the following breaks. Any idea why?</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
      var a = [59, 20, 75, 22, 20, 11, 63, 29, 15, 77]; 
      var result = a.indexOf(32);//
      document.write(result);
  &lt;/script&gt;
  </code></pre>
  
  <p>Error message as below:</p>
  
  <pre><code>SCRIPT438: Object doesn't support property or method 'indexOf' 
  </code></pre>
  
  <p>test.php, line 9 character 1</p>