ServerResponse.write() method tries to write data buffer using libunit
and stores buffers to write in a Server-wide output queue, which is
processed in response to SHM_ACK message from router.
As a side effect 'drain' event implemented and socket.writable flag
reflect current state.
Name and value in each header are 0-terminated, so additional 2 bytes
should be allocated for them. There were several attempts to add these
2 bytes to headers in language modules, but some modules weren't updated.
Also, adding these 2 bytes is specific to the implementation which may be
changed later, so extending this mechanics to modules may cause errors.
The sequence of napi_open_callback_scope(),
napi_call_function(), and napi_close_callback_scope() functions calls
executes the provided JS code and all functions enqueued by
process.nextTick() and Promises during this execution.
This fixes two issues:
- values for mutiple header fields with the same name
passed as arrays were converted to string;
- the type of field value wasn't preserved as required
by specification.
