Log Message:
Update lang/nodejs to 8.4.0.

Update lang/nodejs to 8.4.0.

## 2017-08-15, Version 8.4.0 (Current), @addaleax

- HTTP2
  - Experimental support for the built-in `http2` has been added via the
    `--expose-http2` flag.
- Inspector
  - `require()` is available in the inspector console now.
  - Multiple contexts, as created by the `vm` module, are supported now.
- N-API
  - New APIs for creating number values have been introduced.
- Stream
  - For `Duplex` streams, the high water mark option can now be set
    independently for the readable and the writable side.
- Util
  - `util.format` now supports the `%o` and `%O` specifiers for printing
    objects.

## 2017-08-09, Version 8.3.0 (Current), @addaleax

The V8 engine has been upgraded to version 6.0, which has a significantly
changed performance profile.

- DNS
  - Independent DNS resolver instances are supported now, with support for
    cancelling the corresponding requests.
- N-API
  - Multiple N-API functions for error handling have been changed to support
    assigning error codes.
- REPL
  - Autocompletion support for `require()` has been improved.
- Utilities
  - The WHATWG Encoding Standard (`TextDecoder` and `TextEncoder`) has
    been implemented as an experimental feature.