Firefox has a little middle ground where you can use specific versions outside of the fast release cycle and still get security updates. At least that's the plan. https://wiki.mozilla.org/Enterprise/Firefox/ExtendedSupport:... You don't get the 10 years of support that MSFT might provide for (some) versions of IE, but it's not like you have to upgrade every 6 weeks either. Also, because Firefox is open source, they're hoping that someone else will pick up the slack and continue to support older versions.

I haven't heard of any similar program from Chrome.