Default parameters intermediate scope

[UltCombo]

Adapted test case from this article:

var x = 1;

function foo(x, y = function() { x = 2; }) {
  var x = 3;
  y();
  assert.equal(x, 3); // fails in Traceur
}

foo();
assert.equal(x, 1);

As far as I can see, Traceur does not implement an intermediate scope for default parameters. Has the TC39 changed this behavior, or is this simply a missing feature in Traceur?

[arv]

Yeah, traceur does not do the right thing.

One idea is that if we implement this then we could skip the extra scope if the initializers do not refer to an of the parameters.