How to build PDF file from binary string returned from a web-service using javascript

I am trying to build a PDF file out of a binary stream which I receive as a response from an Ajax request.

Via XmlHttpRequest I receive the following data:

%PDF-1.4....
.....
....hole data representing the file
....
%% EOF

What I tried so far was to embed my data via data:uri. Now, there's nothing wrong with it and it works fine. Unfortunately, it does not work in IE9 and Firefox. A possible reason may be that FF and IE9 have their problems with this usage of the data-uri.

Now, I'm looking for any solution that works for all browsers. Here's my code:

// responseText encoding 
pdfText = $.base64.decode($.trim(pdfText));

// Now pdfText contains %PDF-1.4 ...... data...... %%EOF

var winlogicalname = "detailPDF";
var winparams = 'dependent=yes,locationbar=no,scrollbars=yes,menubar=yes,'+
            'resizable,screenX=50,screenY=50,width=850,height=1050';

var htmlText = '<embed width=100% height=100%'
                     + ' type="application/pdf"'
                     + ' src="data:application/pdf,'
                     + escape(pdfText)
                     + '"></embed>'; 

                // Open PDF in new browser window
                var detailWindow = window.open ("", winlogicalname, winparams);
                detailWindow.document.write(htmlText);
                detailWindow.document.close();

As I have said, it works fine with Opera and Chrome (Safari hasn't been tested). Using IE or FF will bring up a blank new window.

Is there any solution like building a PDF file on a file system in order to let the user download it? I need the solution that works in all browsers, at least in IE, FF, Opera, Chrome and Safari.

I have no permission to edit the web-service implementation. So it had to be a solution at client-side. Any ideas?