March 2018 web platform update

Now widely available on the web platform
Widely available

Array fill(): The fill() method of arrays and typed arrays sets all or some items of an array to a given a value. Learn more.
Array find() and findIndex(): The find() and findIndex() methods of arrays and typed arrays search an array for the first item that satisfies a test function. Learn more.
Flexbox: Flexbox is a one-dimensional layout system, which places content either horizontally or vertically, with optional wrapping. Learn more.
HTTP/2: The HTTP/2 protocol is a major revision of the HTTP network protocol, providing improved performance and efficiency by using a single TCP connection to send multiple streams of data at once. Learn more.
2D transforms: The transform CSS property and its 2D transform functions allow rotating, scaling, skewing, and translating an element. Arbitrary 2D transforms are also possible using a transformation matrix. Learn more.

paint(): The paint() CSS function creates a custom image, drawn using a paint worklet, for an element's background or border. Learn more.
Server timing: The serverTiming property of the PerformanceResourceTiming API contains server timing information about network requests. Learn more.

paint(): The paint() CSS function creates a custom image, drawn using a paint worklet, for an element's background or border. Learn more.
Server timing: The serverTiming property of the PerformanceResourceTiming API contains server timing information about network requests. Learn more.

Sticky positioning: The position: sticky CSS declaration positions an element in the normal flow until it crosses a specified threshold, at which points it becomes fixed (stuck) at that position. Learn more.
WebVTT regions: WebVTT regions set the areas of the video where captions or subtitles should be rendered, such as placing roll-up captions used for live captions. Learn more.

Sticky positioning: The position: sticky CSS declaration positions an element in the normal flow until it crosses a specified threshold, at which points it becomes fixed (stuck) at that position. Learn more.
WebVTT regions: WebVTT regions set the areas of the video where captions or subtitles should be rendered, such as placing roll-up captions used for live captions. Learn more.

Canvas text baselines: The alphabeticBaseline, hangingBaseline, and ideographicBaseline canvas text metrics measure the distance from the used textBaseline to the respective typographic baseline. Learn more.
Promise finally(): The promise finally() method executes a function when the promise settles (resolves or rejects). Learn more.
Storage access: The document.requestStorageAccess() method allows content in iframes to request storing and reading cookies and other site data, while the document.hasStorageAccess() method checks if such access is granted. Learn more.