The form is submitted using ajax, the code above does redirect on the ajax call but not the user page.

What you wan to do is bind a javascript function to the submit botton

$( 'body' ).delegate( 'input[name="ims-add-to-cart"]', 'click', function( e ){
$(document).bind( "ajaxComplete", function(){
window.location = "http://www.google.com/"
})
}