fs: fs.watchFile() should not emit 'stop' event synchronously

[bnoordhuis]

'use strict';
const assert = require('assert');
const fs = require('fs');

const w = fs.watchFile(__filename, () => {});
w.once('stop', assert.fail);  // Should not trigger.
w.stop();
w.removeListener('stop', assert.fail);

That is bad because w.on('stop', w.stop); w.stop(); will result in a 'maximum call stack size exceeded' error.

[claudiorodriguez]

Wrapping https://github.com/nodejs/node/blob/master/lib/fs.js#L1466 in a process.nextTick seems to pass all tests, including the one you put here. I'll make a PR if that makes sense

[claudiorodriguez]

@bnoordhuis would the proposed solution work in your case?

[bnoordhuis]

Can you file a pull request? If it's not a proper solution, the reviewer will tell you.