Unwanted (I think) xulrunner files

I have found on my system a bunch of stuff that seems to belong to the old xulrunner package. There is a /usr/lib/xulrunner directory containing various libraries and also a /usr/include/xulrunner directory. None of these are in the current Firefox footprint. FF now seems to come with its own libxul.so in /usr/lib/firefox. As the separate xulrunner package no longer exists, I can't use prt-get to remove these. Is it safe to just delete them? --