Firefox Release Notes

Improved warning pages for certificate errors and untrusted connections

Enable H.264 if system decoder is available

Enable WebM/VP9 video support on systems that don't support MP4/H.264

In the animation-inspector timeline, lightning bolt icon next to animations running on the compositor thread

Support the brotli compression format via HTTPS content-encoding

Screenshot commands allow user choice of pixel ratio in Developer Tools

Firefox can now get Push Notifications from your favorite sites

Windows XP and Vista screensaver doesn't disable when watching videos (Bug 1193610)

Various security fixes

Firefox has removed support for the RC4 cipher

To support unicode-range descriptor for webfonts, font matching under Linux now uses the same font matching code as other platforms

Firefox will no longer trust the Equifax Secure Certificate Authority 1024-bit root certificate or the UTN - DATACorp SGC to validate secure website certificates

Use a SHA-256 signing certificate for Windows builds, to meet new signing requirements

Stricter validation of web fonts

On-screen keyboard support temporarily turned off for Windows 8 and Windows 8.1

Support for Direct2D 1.0 has been dropped. Windows 7 users can install the Platform Update to re-enable Direct2D support (to fix font rendering issues)

Right click on a logged object in the console to store it as a global variable on the page

Visual tools for Animation:

• View/Edit CSS animation keyframe rules directly in the inspector
• Visually modify the cubic-bezier curve that drives the way animations progress through time
• Discover and scrub through all CSS animations and transitions playing on the page
• Learn more: http://devtoolschallenger.com/

Visual tools for Layout and Styles:

• Display rulers along the viewport to verify size and position and use the measurement tool to easily detect spacing and alignment problems
• Use CSS filters to preview and create real-time effects like drop-shadows, sepia, etc
• Learn more: http://devtoolschallenger.com/

New memory tool for inspecting the memory heap

Service Workers API

Built-in JSON reader to intuitively view, search, copy and save data without extensions

Jump to function definitions in the debugger with Cmd-Click

WebSocket Debugging API and add-on

The rule view now displays styles using their authored text,
and edits in the rule view are now linked to the style editor

Trusteer Rapport is severely impacting the stability of Firefox