May try to run pacman -Sy to update your local package database because as far as I see xulrunner have version 1.9.0.4 in the repos. You can combine the update of the system with a databaseupdate with pacman -Syu

2008/11/23 Martin <marjay@web.de>
Hello all.

If I try to upgrade Mozilla Firefox it doesn't work.

:: Starting full system upgrade...
resolving dependencies...
error: cannot resolve "xulrunner=1.9.0.4", a dependency of "firefox"
error: failed to prepare transaction (could not satisfy dependencies)
:: firefox: requires xulrunner=1.9.0.4

I tried to get xulrunner in AUR but it wasn't there, too.
I thought this could be a good hint for you.
I want to excuse my english, I'm no native speaker and new to Linux.

Greetings,

Martin