Same issue on Cinnamon. There is more description of what is going on
in bug #803165, but I believe I have a simple workaround for now,
which might also work for Gnome/KDE/etc...
mkdir -p ~/.local/share/applications
cp /usr/share/applications/iceweasel.desktop ~/.local/share/applications/
editor ~/.local/share/applications/iceweasel.desktop
Change the Icon line from:
Icon=iceweasel
to:
Icon=/usr/share/icons/hicolor/scalable/apps/iceweasel.svg
Logout and Login
Once the real fix is in place, the new file can and probably should be removed.
On an unrelated note, it would be nice to have a good high contrast
(black and white) icon for Iceweasel, but I'm not much of a graphics
artist =)
Jerad