I can't tell the difference between 18, and 20...So, I want to ask again (and I'm beating a horse that is not only dead, but buried, and decomposed, with only a few bones and other hard items left), what's the point of these fast track updates?
I was happy when Firefox 19 added its own PDF reader like Chrome did long ago. Now Firefox is the default PDF reader on my machine -- I uninstalled Adobe Reader.
At some point recently Firefox made insecure plugins (Flash when outdated, for example) click-to-play by default, which is also nice.
I guess the point is that after the ~6 month wait between Firefox 1, 2, 3, 4, etc. now we no longer have to wait half a year for these small but helpful new features. Security patches are going to happen regularly (monthly?) anyway, so now Mozilla just bundles new features along with the patches.