Not necessary, since we can handle the error properly on the first tick
now, even if there are event listeners, etc.
Additionally, this removes the unnecessary "_needTickCallback" from
startup, since Module.loadMain() will kick off a nextTick callback right
after it runs the main module.
Fix#4856
* Callbacks from spinner now calls its own function, separate from the
tickCallback logic
* MakeCallback will call a domain specific function if a domain is
detected
* _tickCallback assumes no domains, until nextTick receives a callback
with a domain. After that _tickCallback is overridden with the domain
specific implementation.
* _needTickCallback runs in startup() instead of nextTick (isaacs)
* Fix bug in _fatalException where exit would be called twice (isaacs)
* Process.domain has a default value of null
* Manually track nextTickQueue.length (will be useful later)
* Update tests to reflect internal api changes
isaacs
Trevor Norris