JSON on FF issue

[smartpascal]

I had an weird behavior on FF when using JSON type, it seems that the complete event is not firing. On chrome, is working fine. If I remove this object, it will work fine.
{name : 'json', url : 'app.json', data : {description : "manifest file"}}

Note: the response header I'm getting when using
.json --> content-type: "application/octet-stream"
.png --> content-type: "image/x-png"
.jpg--> content-type: "image/pjpeg"
.gif --> content-type: "image/gif"
.svg --> content-type: "application/octet-stream"