Math.round is not a constructor
<p>Consider the following:</p>

<pre><code>x = function () {}
p = new x()
console.log(p) // ok

Math.z = function () {}
p = new Math.z()
console.log(p) // ok 

p = new Math.round()
console.log(p) // TypeError: function round() { [native code] } is not a constructor
</code></pre>

<p>So I can use <code>new</code> with my own functions, but not with <code>Math.round</code>. What makes it so special? Is this documented somewhere?</p>
