Audio & Video

• Audio Data API has been deprecated
• HTMLMediaElement.crossorigin and HTMLInputElement.inputmode have been renamed

Canvas & WebGL

CSS

• CSS3 Flexible Box has been enabled by default
• Initial value for min-width and min-height has been changed back to 0 (even on flex items)
• background-clip and background-origin are now supported in the background shorthand property

DOM

• Regressed Cannot access to frames named sidebar
• HTML elements with tag names bgsound, multicol, and image no longer use the HTMLSpanElement inteface
• Unknown SVG Elements will be SVGElement
• XHR multipart response support has been removed
• HTMLMediaElement.crossorigin and HTMLInputElement.inputmode have been renamed
• LSProgressEvent has been removed
• NamedNodeMap has been renamed to MozNamedAttrMap
• Node.attributes has been removed
• Affecting Node.getUserData() and setUserData() have been removed
• Node.isSupported() has been removed
• NodeIterator.detach() does nothing
• ProgressEvent.initProgressEvent() has been removed
• SVGEvent has been removed

HTML

JavaScript

• ParallelArray is now disabled in Beta, Release and ESR

Miscellaneous

• Reverted RFC 2047 encoding support for HTTP header field parameters has been removed

Networking

• Reverted Third-party cookies are blocked by default

Plug-ins

Privacy & Security

• Reverted Third-party cookies are blocked by default

SVG