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.
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