mainly to allow native addons to export single functions on
rather than being restricted to operating on an existing
object.
Init functions now receive exports as the first argument, like
before, but also the module object as the second argument, if they
support it.
Related to #4634
cc: @rvagg
It was decided that the performance benefits that isolates offer (faster spin-up
times for worker processes, faster inter-worker communication, possibly a lower
memory footprint) are not actual bottlenecks for most people and do not outweigh
the potential stability issues and intrusive changes to the code base that
first-class support for isolates requires.
Hence, this commit backs out all isolates-related changes.
Good bye, isolates. We hardly knew ye.
