Printing in Firefox last portion of long image is skipped

Question

I'm working in printThis.js. In IE and Chrome printing is working fine but in Firefox image bottom portion in printing is cutoff. What am I missing? See this JS Fiddle

Here is what I have done so far

 $(document).ready(function () { //fire on DOM ready            

     $('#dvPrint').click(function () {
         $('#comparisonImage').printThis({
             pageTitle: "Site Comparison",
             importCSS: true,
             debug: true,
             printMode: 'popup'
         });
     });
 });