Firefox 46 for developers

Highlights:

• Dominators view in the Memory tool
• Allocations view in the Performance tool
• One click to apply @media rule conditions in the Style Editor

All devtools bugs fixed between Firefox 45 and Firefox 46.

• When faced with an invalid type value, <ul> no longer maps to decimal, but now behaves as if no type value were specified (Firefox bug 241719).
• The attribute pattern on <input> is now treated as a regular expression with "u" (unicode) flag (Firefox bug 1227906).

• Our implementation of CSS Grids has been updated:
  • The keywords auto-fill and auto-fit are now allowed in the repeat() function (Firefox bug 1118820).
  • The true value has been renamed to unsafe; this affects the properties justify-content, align-content, justify-self, align-self, justify-items and align-items (Firefox bug 1230478).
• The properties text-emphasis, text-emphasis-style, text-emphasis-color and text-emphasis-position are now enabled by default (Firefox bug 1231485).
• Gecko now accepts the -webkit- prefixed version of some properties; it requires to switch layout.css.prefixes.webkit to true (Firefox bug 1213126).
• The experimental support of the font-display descriptor (of @font; it requires to switch layout.css.font-display.enabled to true (Firefox bug 1157064).
• Added support for @media (-webkit-transform-3d) as a media query for 3D transform support, if about:config pref layout.css.prefixes.webkit is set to true (Firefox bug 1239799).
• linear-gradient() support for the omission of 0deg units (Firefox bug 1239153).
• Added -webkit-filter for web compatibility, behind the preference layout.css.prefixes.webkit, defaulting to false (Firefox bug 1236506).
• [css-align] "unsafe start" (formerly "true start") should serialize to "start" etc (Firefox bug 1230398).

• The ES2015 RegExp unicode (u) flag has been implemented (Firefox bug 1135377).
• The ES2015 block-level functions have been implemented (Firefox bug 1071646).
• The ES2015 TypedArray.prototype.sort() method has been implemented (Firefox bug 1121937).
• The ES2015 arguments[@@iterator] has been implemented (Firefox bug 1067049).
• The experimental ECMAScript Shared Memory API has been implemented. See the SharedArrayBuffer and Atomics objects. To use this experimental API set javascript.options.shared_memory to true in about:config.
• Redeclaration of let and const variables now throws a SyntaxError instead of a TypeError as per the ECMAScript specification (Firefox bug 1198833).
• In Strict mode, setting properties on primitive values will now throw a TypeError (Firefox bug 603201).
• The non-standard WeakMap.prototype.clear() and WeakSet.prototype.clear() methods have been removed (Firefox bug 1101817).
• The non-standard, static RegExp.multiline property is now deprecated (Firefox bug 1220457).
• Built-in accessor function names now have a "get" or "set" prefix (Firefox bug 1180290, Firefox bug 1235656).
• JS1.7/JS1.8 (legacy) array comprehensions and JS1.7/JS1.8 (legacy) generator comprehensions have been removed (Firefox bug 1220564).

DOM & HTML DOM

• The deprecated Window.showModalDialog() method is no more available when Firefox runs in multi-process mode (e10s) (Firefox bug 1234700).
• Added support for Document.elementsFromPoint() (Firefox bug 1164427).
• When a non-existent option of a <select> element is programmatically selected, instead of being incorrectly left unchanged, the selectedIndex value is now set to -1, the selectedOptions to an empty HTMLCollection, and value to an empty string (Firefox bug 1203668).

Canvas

• The remaining parts of the experimental OffscreenCanvas API has been implemented; new features: OffscreenCanvas() constructor, OffscreenCanvas.toBlob(), and OffscreenCanvas.transferToImageBitmap(). To use this experimental API set gfx.offscreencanvas.enabled to true in about:config (Firefox bug 1172796).
• The ImageBitmap.close() method is now supported (Firefox bug 1172796).
• A new ImageBitmapRenderingContext rendering context is now implemented. Use "bitmaprenderer" with OffscreenCanvas.getContext() or HTMLCanvasElement.getContext() to obtain this context. (Firefox bug 1172796).

WebGL

• The WEBGL_compressed_texture_etc extension has been implemented, allowing the use of ETC2 compressed texture formats (Firefox bug 917505). To use this extension, set the preference webgl.enable-draft-extensions to true in about:config.

IndexedDB

No change.

Service Workers

• FetchEvent.request is now non-nullable (see Firefox bug 1238213.)
• Navigator.serviceWorker has now been marked as SameObject (see Firefox bug 1238205.)
• ExtendableMessageEvent.ports has now been marked as SameObject (see Firefox bug 1238225.)

Fetch

• Request.mode now has a new value available, navigate, for supporting requests generated while navigating between documents (see Firefox bug 1209081.)

WebRTC

• The RTCPeerConnection.createOffer() method now supports the VP9 video codec, although this is disabled by default. To enable it, set the preference media.peerconnection.video.vp9_enabled to true in about:config. When enabled, VP9 is the preferred codec; previously VP8 was preferred (Firefox bug 1242324).
• The method RTCRtpSender.setParameters() has been added to allow changing the values of parameters after the RTCRtpSender was initially created.

New APIs

• In SVG, the SVGStyleElement interface now implements the LinkStyle mixin ) Firefox bug 1239128.

Miscellaneous

• The asynchronous FileReader is now available in Web workers (Firefox bug 901097).
• Our experimental implementation of Web Animations API has been updated:
  • AnimationEffectTimingReadOnly and AnimationEffectReadOnly.timing have been implemented (Firefox bug 1214536).
• The Permissions API has now been enabled by default, for all release versions, not just Nightly as it previously was (Firefox bug 1221106.)
• Sanitization of WOFF fonts has been loosened a bit (Firefox bug 1244693).

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• Support of RFC 7686 has been added: by default there is no attempt to resolve domain with the TLD .onion. This is controlled by the preference network.dns.blockDotOnion. Add-ons supporting Tor can swap this pref. (Firefox bug 1228457)

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