title: Number.isNaN doesn't exist in IE
body: <p>Why does not IE support the <strong>Number.isNaN</strong> function? I can't use simple isNan instead of Number.isNaN 'cause these functions are different!
  For example:</p>
  
  <pre><code>Number.isNaN("abacada") != isNaN("abacada") //false != true
  </code></pre>
  
  <p>I need to abstract string and number and check, is some var really contains <strong>NaN</strong> (I mean NaN constant, but not-a-number value like strings).</p>
  
  <pre><code>someobj.someopt = "blah"/0;
  someobj.someopt2 = "blah";
  someobj.someopt3 = 150;
  for(a in someobj) if(Number.isNaN(someobj[a])) alert('!');
  </code></pre>
  
  <p>That code should show alert for 1 time. But if I will change Number.isNaN to isNaN, it will alert 2 times. There are differences.</p>
  
  <p>May be there is some alternative function exists?</p>