[node] Add definition for Node.js v8

[ikokostya]

List of changes:

• Move current types/node/index.d.ts to types/node/v7/index.d.ts
• Remove util.promisify (introduced by [types/node] Add promisify to util [wip] #16946) from v7/index.d.ts, because this function is available since Node.js v8.
• Use types/node/index.d.ts for Node.js v8 - increase the version number in the header.
• Change compilerOptions.lib to es6 in tsconfig.json like in types/node/v6/tsconfig.json.

---

Please fill in this template.

• Use a meaningful title for the pull request. Include the name of the package modified.
• Test the change in your own code. (Compile and run.)
• Follow the advice from the readme.
• Avoid common mistakes.
• Run npm run lint package-name (or tsc if no tslint.json is present).

Select one of these and delete the others:

If changing an existing definition:

• Provide a URL to documentation or source code which provides context for the suggested changes: https://nodejs.org/dist/latest-v8.x/docs/api/
• Increase the version number in the header if appropriate.
• If you are making substantial changes, consider adding a tslint.json containing { "extends": "dtslint/dt.json" }.

[dt-bot]

types/node/index.d.ts

to authors (@DefinitelyTyped/DefinitelyTyped @parambirs @robdesideri @tellnes @WilcoBakker Microsoft TypeScript (account can't be detected)). Could you review this PR?
👍 or 👎?

Checklist

• pass the Travis CI test?

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types/node/v7/index.d.ts

Checklist

• is correct naming convention?
  • https://www.npmjs.com/package/node
  • http://bower.io/search/?q=node
  • others?
• has a test file? (node-tests.ts or node-tests.tsx)
• pass the Travis CI test?

[ghost]

See #16860.
This branch doesn't seem to make any type changes to node/index.d.ts.

[ikokostya]

@andy-ms Now users can add features to declaration for Node.js v7 which doesn't exist in Node.js v7 runtime.

There are several problems:

• Code will be compiled with such definition, but will fail at runtime.
• People can start to use declaration for Node.js v7 with Node.js v8 runtime. After that, removing anything related to Node.js v8 from v7 definition potentially can brake many modules.

If separated issue (#16860) for Node.js v8 exists, why pull request with util.promisify was merged?

[hinell]

@ikokostya This solution doesn't seem solve broken runtime anyway cause there are plenty modules that just referencing the latest DT/node/index.d.ts version in their dependencies meaning moving index.d.ts to separate folder won't help. Though I like idea to keep separate versions.

[ikokostya]

So @yuit @andy-ms what we wait here? Could you provide TODO list of necessary changes for Node.js 8 #16860 (comment)?

[minestarks]

@andy-ms to close the loop. I don't see a reason not to merge this. It'll keep people from adding v8 features to v7 typings. Any objections?

[magnushiie]

It seems this has not been published to @types/node npm package yet? The latest version of that package is 7.0.31

[minestarks]

@magnushiie check again, it's up

[magnushiie]

Thanks!