It appears that r75077 broke the JS on the product 3.6 firstrun page (when it got pushed to production in r76046). The newsletter-form.js file is no longer being included. Fortunately, the page was coded such that it fails gracefully without JS and links to the newsletter signup page instead of the in-line form.
Hey Anthony, I think this is probably already taken care of in your latest patches. Can you make sure this is fixed on trunk?
Yes, this is fixed on trunk. Please review and push to production my patch in bug 589315. This will degrade performance (which was the primary goal) but I'll make improvements later.
This was fixed inadvertently through another bug.
verified fixed http://www.mozilla.com/en-US/firefox/3.6/firstrun/