Don't allow changing document.domain value
<p>I need to deny changing <code>document.domain</code>. Say, if I run this code at <em>foo.boo.com</em></p>

<pre><code>Object.defineProperty(document, 'domain', { 
    get: function () {
        return 'foo.boo.com';
    }
});
</code></pre>

<p>and then will it be possible to set <code>document.domain</code> to <em>boo.com</em>? I ask because I want to deny changing <code>document.domain</code> by untrusted code. </p>
