Follow up to #5090

[Timer]

Following up on #5090, it looks like Array.from is required.

Unfortunately, it looks like babel wastes a lot of bytes by duplicating helpers:

(window.webpackJsonp = window.webpackJsonp || []).push([
 [0],
 [
 function(r, t, n) {
 r.exports = n(1);
 },
 function(r, t, n) {
 'use strict';
 n.r(t);
 var e,
 o = new Set([9, 8, 7]),
 a = [1, 2, 3].concat(
 (function(r) {
 if (Array.isArray(r)) {
 for (var t = 0, n = new Array(r.length); t < r.length; t++)
 n[t] = r[t];
 return n;
 }
 })((e = o)) ||
 (function(r) {
 if (
 Symbol.iterator in Object(r) ||
 '[object Arguments]' === Object.prototype.toString.call(r)
 )
 return Array.from(r);
 })(e) ||
 (function() {
 throw new TypeError(
 'Invalid attempt to spread non-iterable instance'
 );
 })()
 );
 function i(r) {
 return (
 (function(r) {
 if (Array.isArray(r)) {
 for (var t = 0, n = new Array(r.length); t < r.length; t++)
 n[t] = r[t];
 return n;
 }
 })(r) ||
 (function(r) {
 if (
 Symbol.iterator in Object(r) ||
 '[object Arguments]' === Object.prototype.toString.call(r)
 )
 return Array.from(r);
 })(r) ||
 (function() {
 throw new TypeError(
 'Invalid attempt to spread non-iterable instance'
 );
 })()
 );
 }
 var c = new Set([4, 5, 6]);
 console.log([1, 2, 3].concat(i(c), i(a)));
 },
 ],
 [[0, 1]],
]);
//# sourceMappingURL=main.91f74b1f.chunk.js.map

from:

// src/index.js
import { c } from './boo';
const a = [1, 2, 3];
const b = new Set([4, 5, 6]);

console.log([...a, ...b, ...c]);

// src/boo.js
const d = [1, 2, 3];
const e = new Set([9, 8, 7]);
const c = [...d, ...e];
export { c };