To read: Mozilla Firefox Release Notes

Installation :
yum --enablerepo=remi update firefox

Notice : this RPM is very close of Firefox 21 one from Fedora 17/18/19.

This package needs xulrunner-last which install beside default one.

Warning : during first launch, an English dialog (Select your Add-ons) will ask you to validate the installed extensions. It is mandatory to check the "Keep" box for the "Language Pack", else Firefox will be displayed in English (you can enabled it later from the  Tools / Add_ons / Languages menu). See Bug #963422.

For Enterprise Linux 6, the build use python2.7 available as a SoftwareCollection. (only for build, unneeded at run time).

RPM are available for Fedora 14 (x86_64), 15 et 16 and, for Enterprise Linux 6.