do not use process.nextTick without check that it exists

[nosovk]

if we do not add shims to browser process.nextTick does not exist, because of missing process.
In v8 eventloop sequence is:

process.nextTick(callback) // runs first, after current Tick
setTimeout(callback, 0) // runs after nextTick
setImmediate(callback) // runs after all (https:/nodejs/node-v0.x-archive/issues/25788#issuecomment-128869483)

That's why where is possible (in destructors) process.nextTick substituted with setTimeout.
Where it's significant - substitution will be done if process.nextTick is missing.

[artesan-1]

Are you sure that any dependant packages don't have the same behavioure?