Renaming function arguments doesn't play well with ES6 object shorthand

[RyanZim]

Input:

function foo (a, b) {
  return {a, b}
}

Expected Output:

function foo(a,b){return {a,b}}

Actual Output:

function foo(n,r){return{a:n,b:r}}

This is wasting bytes. Don't know if this is common enough in real-world code to optimize, but just thought I'd point it out.

[Conduitry]

This has already come up in #72 but it might still make sense to have a narrower ticket just for this issue.

[RyanZim]

Ah, sorry. Didn't see that issue.

I think shorthand properties is (currently) the only place where this could happen

So I think I'll close this.