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.
Only node.cc, stream_wrap.cc, and tcp_wrap.cc have been done. The rest still need work.