use the property name _onTimeout
so that the global clearTimeout
method in Node will make it no-op if it gets passed there.
Clock governing this timer
set by Timer#unref
These timers don't keep the event loop open anyway, so this doesn't do much, but it's useful when testing to ensure that a timeout had .ref() or .unref() called on it.
When this timer should fire
A Timer that lives in the mock clock