Firefox 47.0, June 6, 2016
https://www.mozilla.org/en-US/firefox/47.0/releasenotes/
New
Support for Google’s Widevine CDM on Windows and Mac OS X so streaming services like Amazon Video can switch from Silverlight to encrypted HTML5 video.
Enable VP9 video codec for users with fast machines
Embedded YouTube videos now play with HTML5 video if Flash is not installed.
View and search open tabs from your smartphone or another computer in a sidebar
Allow no-cache on back/forward navigations for https resources
Latgalu [ltg] locale added. Wikipedia tells us there are 164,500 daily speakers.
Fixed
Various security fixes
Changed
FUEL (Firefox User Extension Library) has been removed. Add-ons relying on it will stop working.
The browser.sessionstore.restore_on_demand preference has been reset to its default value (true) to avoid e10s performance problems. Because faster is better!
The Firefox click-to-activate plugin whitelist has been removed.
HTML5
cuechange events are now available on TextTrack objects
WebCrypto: PBKDF2 supports SHA-2 hash algorithms
WebCrypto: RSA-PSS signature support
Known issue with old invalid paper size printing prefs (Bug 1276717)
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Available via the program's internal updater: Help / About Firefox