Firefox Beta and Developer Edition
Release Notes

Instant browser tab sharing through Hello

Tabs synced via Firefox Accounts from other devices are now shown in dropdown area of Awesome Bar when searching

Synced Tabs button in button bar

GTK3 integration (GNU/Linux only). Disabled after beta 4

Introduce a new preference (network.dns.blockDotOnion) to allow blocking .onion at the DNS level

Guarani [gn] locale added

URLs containing a Unicode-format Internationalized Domain Name (IDN) are now properly redirected

Tab Groups (Panorama) feature removed

List of animated properties and keyframes is now displayed when clicking on an animation in the animation-inspector’s timeline

Inspector search now matches results from all content in the page, including subframes

Support for diffing heap snapshots added to the memory tool

Added Negative url filtering for the network monitor

DOMContentLoaded and load events shown in the network monitor timeline

Fine tune animations by changing the playback rate of animations in the animation-inspector's timeline

Ability to filter snapshot output in memory tool

Push API support, part of Progressive Web Applications

ES6 Classes

Support delivery of a Content Security Policy (CSP) via a meta tag