Remi published Firefox 19 for older Fedora releases (Fedora 15 and 16) as well as for RHEL6 and other enterprise clones (CentOS, Scientific Linux). The update is surely welcome for those who use CentOS 6 as a desktop OS (myself included) and don’t want to stick with the default ESR version of Firefox (even though that also received an important update to ESR 17 as announced by Red Hat).
To install Firefox 19 on CentOS 6 you need the Remi repository as well as the EPEL repo as a dependency:
yum localinstall epel-release-6-8.noarch.rpm remi-release-6.rpm
yum --enablerepo=remi update firefox
Now you can enjoy the native PDF browser support on your enterprise OS!