Prevent EMFILE #10432

Try to run (with empty file.txt in working dir):

for(let i = 0; i < 10e3; i++) { require('fs').watch('file.txt') }

Produces instantly: Uncaught Error: watch file.txt EMFILE

It make sense to dedupe multiple watchers on same file to prevent 'too many files open'?

• Version: v7.2.1
• Platform: macOS