title: Number.isInteger(x) which is created can not work in IE
body: <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>Number.prototype.isInteger = Number.prototype.isInteger || function(x) {
    return (x ^ 0) === x;
  }
  console.log(Number.isInteger(1));</code></pre>
  </div>
  </div>
  </p>
  
  <p>will throw error in IE10 browser</p>