parseInt misbehaves when passed as argument to a map call
<p>Why is this happening?</p>

<pre><code>var numbers = [ '1', '2', '3', '4' ];
var intNumbers = numbers.map( parseInt ); // intNumbers = [1, NaN, NaN, NaN]
var fltNumbers = numbers.map( parseFloat ); // fltNumbers = [1, 2, 3, 4, 5 ]
</code></pre>

<p>But <code>Array.prototype.map.call( numbers, parseInt );</code> returns <code>[ 1, 2, 3, 4];</code>. I'm running this code in Google Chrome 26.0.1410.65.</p>
