May 2018 web platform update

Now widely available on the web platform
Widely available

initial: The initial keyword resets any CSS property to its initial value as defined by the specification. For example, the initial value of the display property is inline, regardless of the element being styled. Not to be confused with revert, which resets to the user or browser default style. Learn more.
<template>: The <template> HTML element holds HTML fragments which you can clone and insert into the document using JavaScript. Learn more.

Array iterators: Arrays are iterable with the for … of statement and enumerable with the methods entries(), keys(), and values(). Learn more.
JavaScript modules: JavaScript modules allow code to be organized into reusable units. Modules use import to load other modules and export to declare what is available to import from other modules. In HTML, modules are loaded with <script type="module">. Learn more.