After six months, zero progress on fixing it.
According to the bug, it was fixed in an upstream pull request yesterday. Given the usual rate at which upstream pdf.js updates are landed for downstream Firefox, it's very likely the fix will be in Firefox 28. Of course, you can confirm it's fixed in a development build of pdf.js whenever you want: https://github.com/mozilla/pdf.js#browser-extensions
You will lose an important tape file.