JS error in IE7 / IE8 : 'var' has value Null or is not an object
<p>This snippet just makes IE7/IE8 crashes the page throwing error. I don't know why cause on chrome / FF, everything is fine.</p>

<p><a href="http://jsfiddle.net/Zrz9t/15/" rel="nofollow">http://jsfiddle.net/Zrz9t/15/</a></p>

<p>The problem seems to be here :</p>

<pre><code>            return event.Date.valueOf() === date.valueOf();
</code></pre>

<p>The error is :</p>

<p>Message:  <strong>'Date' has value Null or is not an object</strong></p>

<p>What's causing this ? Thanks</p>

<p><strong>EDIT</strong> I updated my code here <a href="http://jsfiddle.net/Zrz9t/15/" rel="nofollow">http://jsfiddle.net/Zrz9t/15/</a></p>
