this returns the wrong date when subtracted
<p>Why when I subtract these two dates do I get the wrong answer</p>

<pre><code>var a = new Date("1990","0","1");
var b = new Date("1900","0","1");

var x = new Date(a - b);

console.log(x);

answer: Date {Thu Jan 01 1880 02:00:00 GMT+0200 (South Africa Standard Time)}
</code></pre>

<p>How do I make it return : 90 years and 0 days and 0 months</p>
