I'm not sure about the audience here on hacker news, but I can image many are more interested in the developer release notes:
https://developer.mozilla.org/en-US/Firefox/Releases/51#Chan... (e.g. JS/CSS api changes).
Aside; the FF dev release notes always impress upon me the scale of modern browsers. There's just so much new stuff, and lots of it isn't trivial at all, and that's despite the rather rapid release calendar, and the need to be pretty much rock solid on a huge variety of systems, and the list of tricky non-functional aspects like perf, size, security, maintainability, etc. that all this code needs to at least consider. It's daunting.
Re:Firefox 51.0
by em3rgent0rdr on Tuesday January 24, 2017 @04:41PM
(#13475824)
FLAC yes!
Some of the highlights:
* Users can view passwords in the save password prompt before saving them
* Firefox will save passwords even in forms that do not have “submit” events
* A warning is displayed when a login page does not have a secure connection
* Improved video performance for users without GPU acceleration for less CPU usage and a better full screen experience
* Added support for WebGL 2, with advanced graphics rendering features like transform feedback, improved texturing capabilities, and a new sophisticated shading language
* Added support for FLAC (Free Lossless Audio Codec) playback