IE conditional statements in Jade template engine

How can I convert following IE conditional statements in JADE language :

<!--[if IE 8]> <html lang="en" class="ie8"> <![endif]-->
<!--[if IE 9]> <html lang="en" class="ie9"> <![endif]-->
<!--[if !IE]><!--> <html lang="en"> <!--<![endif]-->

I have tried following but it is not working:

//if IE 8
    html lang="en"  class="ie8"
//if IE 9
    html lang="en" class="ie9"
//if !IE
    html lang="en"
// <![endif]

It is showing following output :

<!--if IE 8html lang="en"  class="ie8"
-->
<!--if IE 9html lang="en" class="ie9"
-->
<!--if !IEhtml lang="en"
-->
<!-- <![endif]-->

Can some one guide me how it can be rectified.