Better `filter.js` benchmark

[ChocolateLoverRaj]

There are many things I would like to change:

• arr-diff/benchmark/code/filter.js

  Line 3 in ea84b7d

  module.exports = function diff(arr, arrays) {

  Uses function instead of arrow function

• arr-diff/benchmark/code/filter.js

  Line 3 in ea84b7d

  module.exports = function diff(arr, arrays) {

  Uses arrays for a parameter, but is actually used like const arrays =. Uses arguments, when it could use ...arrays.

• arr-diff/benchmark/code/filter.js

  Line 4 in ea84b7d

  arrays = [].concat.apply([], [].slice.call(arguments, 1));

  This is a really wierd line. Can just use [].concat() instead of [].concat.apply(). Uses [].slice when Array.prototype.slice makes more sense.

• arr-diff/benchmark/code/filter.js

  Line 6 in ea84b7d

  return arrays.indexOf(ele) === -1;

  Can use includes instead of indexOf

Can I make a pull request changing this? Should I add a new benchmark or edit the existing one?