it's 3.31.3 release day, upload a tarball and show that our software is more stable than this table 彡┻━┻
In dropping the support for creating website links from Firefox drops,
commit 0e0f5b9a also removed the ability to handle _NETSCAPE_URLs at all.
Re-add the necessary bits for drag'n'drop downloads to work as they did
in GNOME 3.28.