Apple pushes out third Safari Technology Preview release

JavaScript

• Added support for Symbol.isConcatSpreadable per the ES6 spec
• Made RegExp constructor get the Symbol.match property to decide if an object should be constructed like a RegExp object per the ES6 spec
• Changed String.match and String.search to use RegExp constructor per the ES6 spec
• Corrected how function declarations are hoisted per the ES6 spec
• Improved parsing of ES6 arrow functions
• Added RegExp.prototype[@@split] and made String.prototype.split use it per the ES6 spec
• Added RegExp.prototype[@@search]
• Updated the treatment of invoking methods on RegExp.prototype per the ES6 spec
• Made more test cases pass with ES6 RegExp unicode flag
• Added support for caching accesses to arguments.length for a performance speed-up
• Corrected the behavior of throw() for generators yielding to an inner generator per draft ECMAScript spec

CSS

• Implemented the functional :host() pseudo class
• Improved support for SVG cursor images
• Started using OpenType math fonts by default for MathML
• Fixed measurement of hanging punctuation
• Improved hyphenation when the last line in a paragraph only contains one syllable of a word
• Fixed a layout problem affecting CSS Grid items without a static inline position in RTL languages
• Fixed positioned items with gaps for CSS Grid
• Added support for CSS Grid grid-template-columns repeat(auto-fill, …) and repeat(auto-fit, …)
• Fixed positioned items with content alignment in CSS Grids
• Started using grid-template-areas to determine the explicit grid
• Corrected CSS Grid layout by using the margin box for non-auto minimum sizes

Web APIs

• Added support setting and retrieving Blob values in IndexedDB
• Corrected MessageEvent.source result once window has been fully created
• Improved stability when the first child of a shadow root is a comment node
• Made CSS be a proper constructor on the window object with static functions
• Exposed the Crypto constructor on the window object
• Added support for display: contents on elements
• Fixed FontFace so it will be properly reject the returned promise if Content Security Policy blocks all the URLs
• Made FontFaceSet handle null correctly
• Corrected DOMTokenList.contains() so it does not throw an exception
• Made Selection.deleteFromDocument not delete a character when the selection is a caret per the spec
• Improved the IndexedDB bindings to better match the spec
• Made AudioBufferSourceNode.buffer nullable
• Improved stability handling a wheel event that closes a frame

Web Inspector

• Made it possible to expand objects in the Instances heap snapshot view to see what it retains
• Improved performance dramatically in the Timelines tab when recording pages with a lot of rapid activity and for long recordings
• Improved JavaScript pretty printing performance by using Esprima and by no longer blocking the main thread
• Improved the profiler's sampling rate to get closer to a 1ms sample frequency
• Improved filtering in Open Quickly dialog
• Made the Open Quickly dialog keep its resource list up to date
• Stopped trying to match color patterns in JavaScript source code to improve performance of large resources
• Changed take snapshot navigation button to a camera glyph
• Corrected source code location links in the JavaScript profile Call Trees view
• Made XHRs and Web Workers full-text searchable
• Improved the appearance of DOM nodes in object previews
• Improved the tab bar rendering when the tabs are small
• Corrected dock controls disappearing from the toolbar after leaving fullscreen
• Started remembering the zoom factor as a persistent setting across sessions
• Corrected sourceMappingURL not being used when sourceURL was also set
• Started localizing sizes and times by using Number.prototype.toLocaleString
• Made sourceMappingURL work more reliably across reloads

Rendering

• Improved the time to display for some pages — allowing a short page header to render immediately before other content populates later
• Fixed page tile layers disappearing when graphics acceleration is unavailable
• Made font-size: 0 render as 0 width when text-rendering: optimizeLegibility is used
• Corrected focus ring drawing at incorrect location on image map with a CSS transform
• Made negative letter-spacing affect the right edge of the content's visual overflow
• Corrected compositing for WebGL based canvases after they changed size
• Started clearing the rendered icon on < input type=file > when an empty files list is set
• Improved performance of border-collapse: collapse on tables
• Improved rendering of select[multiple] to better match other browsers
• Fixed backdrop filter so it honors visibility: hidden

Security

• Made nested browsing context created for object or embed respect Content Security Policy's object-src directive
• Started ignoring Content Security Policy meta tags if it is not a descendent of per the spec
• Started ignoring report-only Content Security Policy directives delivered via meta tag per the spec
• Started ignoring paths in Content Security Policy URL matching after redirects per spec
• Removed support for X-Frame-Options in per the spec

Networking

• Stopped speculatively revalidating cached redirects
• Stopped cacheing responses with Content-Range headers to avoid serving incorrect results
• Fixed clearing the application cache when removing website data in Privacy preferences

Accessibility

• Changed the application role description to "web application" to avoid confusion with the top-level system application description
• Made presentation role be preferred over child