PDF files cannot be downloaded in Tor Browser 4.5 via the PDF viewer

PDF files cannot be downloaded in Tor Browser 4.5 anymore. One gets an error back:

************************************************************
* Call to xpconnect wrapped JSObject produced this error:  *
[Exception... "Access to restricted URI denied"  code: "1012" nsresult: "0x805303f4 (NS_ERROR_DOM_BAD_URI)"  location: "<unknown>"]
************************************************************

This is working fine in 4.5a5. Looking at the fix for #15502 (moved) I highly suspect this is the culprit.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information