Firefox Beta and Developer Edition
Release Notes

Updated Firefox Login Manager to allow HTTPS pages to use saved HTTP logins. It’s one more way Firefox is supporting Let’s Encrypt and helping users transition to a more secure web.

Added features to Reader Mode that make it easier on the eyes and the ears

• Controls that allow users to adjust the width and line spacing of
  text
• Narrate, which reads the content of a page out loud

Improved video performance for users on systems that support SSSE3 without hardware acceleration

HTML5 audio and video improvements

• Files can now be looped through the built-in controls in the context menu
• Play audio and video at 1.25× speed through the context menu

Enhancements for Mac users

• Improved performance on OS X systems without hardware acceleration
• Improved appearance of anti-aliased OS X fonts

Reader Mode can now read articles out loud

Improved appearance of anti-aliased OS X fonts

Support of Widevine CDM through the EME API under GNU/Linux

Fixed an issue that prevented users from updating Firefox for Mac unless they originally installed Firefox. Now, those users as well as any user with administrative credentials can update Firefox.

Ended Firefox for Mac support for OS X 10.6, 10.7, and 10.8.

Ended Firefox for Windows support for SSE processors

Removed Firefox Hello

Re-enabled the default for Graphite2 font shaping

Block some nonessential Flash plugin content

Added a Cause column to the Network Monitor to show what caused each network request

Introduced web speech synthesis API