CSS

• Added discrete animation support for grid-template-columns and grid-template-rows (r278173)
• Added support for calc() on components inside relative color syntax colors (r278261, r278304)
• Added support for “relative color syntax” for color() (r278364)
• Added additional target luminance keywords for color-contrast() (r278262)
• Fixed the height of an empty table inside an orthogonal flex parent (r277777)
• Fixed will-change: position to only create a containing block for position: absolute elements (r277579)
• Made will-change: transform-style create a containing block (r277566)
• Fixed percent calculations for padding-top and padding-bottom when the parent has padding (r278194)

Scrolling

• Fixed scroll snapping in non-horizontal writing modes (r278350)
• Fixed layout issue handling changes to scroll-snap properties (r278193)
• Improved scrolling performance when background-attachment: fixed is used inside a position: fixed layer (r278419)
• Improved how the current document scroll position is maintained on full page zoom (r277775)

JavaScript

• Added support for Ergonomic Brand Checks proposal (e.g. #x in object) behind the--usePrivateIn flag (r277926)
• Fixed private static method in class-scope (r278510)
• Optimized Function.prototype.toString (r278462)
• Optimized in with non-identifier via non ad-hoc IC (r278445)

Media

• Added MediaSession.callActionHandler (r278222)
• Fixed MediaSession action handlers to be treated as having a user gesture (r277588)
• Fixed macOS WebM Format Reader returning enabled for tracks that do not have samples (r278155)
• Added support for H.264 profiles in MediaRecorder (r278158)

WebRTC

• Changed to tighter bitrate allocation rules for WebRTC H.264 software encoder (r278272)

Web API

• Added support for creating, accessing, and setting non-sRGB ImageData via canvas (r277569)
• Added support for dispatching wheel events with ctrlKey on pinch gestures, which is commonly used for zooming embedded maps (r277772)
• Fixed the value of a color input to update visually when using setAttribute (r277778)

Accessibility

• Fixed increased contrast not detected in the browser until an additional setting is applied (r277971)
• Fixed accessibility caption styles to always reflect the selection (r277874)

Rendering

• Enabled <summary> to be a flex container (r278280)
• Changed grid track size to reject a unit-less length (r277868)
• Fixed incorrect selection when a tall float element is present (r278379)
• Fixed incorrect text selection when crossing a flex item boundary (r278411)