Firefox Beta and Developer Edition
Release Notes

Mac OS X command-E sets find term to selected text

Ignore autocomplete="off" when offering to save passwords via the password manager (see 956906)

TypedArrays don't support new named properties (see 695438)

Disallow calling WebIDL constructors as functions on the web

With the exception of those bundled inside an extension or ones that are whitelisted, plugins will no longer be activated by default (see blog post)

Support for GStreamer 1.0 (see 806917 for build configuration)

Fixes to box-shadow and other visual overflow (see bug 480888)

Mute and volume available per window when using WebAudio

background-blend-mode enabled by default

Use of line-height allowed for <input type="reset|button|submit">

ES6 array and generator comprehensions implemented (read docs for more details)

Error stack now contains column number

Support for alpha option in canvas context options (feature description)

Mac OS X: cmd-L no longer opens a new window when no window is available (1008793)

Text Rendering Issues on Windows 7 with Platform Update KB2670838 (MSIE 10 Prerequisite) or on Windows 8.1 has a workaround (see 812695)

Without affecting security, after restoring your session, Extended Validation Certificates might not display (See 995801)

Slow shut downs lead to 'Firefox is already running' warning (see 966469 and 985655)

Exit is not always completed when "clear history when Firefox closes" is enabled (1005487)