Compiler produces invalid Array().keys().slice() output

[alextreppass]

I was looking for a compact way to write a 'range' function and stumbled across this stackoverflow answer.

The spread operator variant compiles successfully but the output is not valid.

TypeScript Version: 2.5.2

Code

// expected output
const expected = [0, 1, 2, 3, 4];

// works in vanilla JS
// breaks in TS
// compiles to `Array(5).keys().slice()` which breaks as keys() returns an Iterator
const withSpread = [...Array(5).keys()];

// works in vanilla JS
// works in TS
// compiles to `Array.from(Array(5).keys())`
const from = Array.from(Array(5).keys());

Expected behavior:
The withSpread variant should produce valid JS that generates [0, 1, 2, 3, 4]

Actual behavior:
Resulting JS throws TypeError: Array(...).keys(...).slice is not a function

[ikatyang]

Target es5 -> --downlevelIteration
Target es6 -> --target es6

[alextreppass]

Thank you! The compiler didn't give any warnings - just produced invalid code.