Finalized namespace objects should have properties assigned as if by Array#sort.

From our earlier chat discussion I mentioned an interesting case form the mutual-all cyclical tests that we produced a namespace object of `{ b: "b", a: "a" }` while browsers produced `{ a: "a", b: "b" }`. It turns out it's because of [step 7 of this rule](https://tc39.github.io/ecma262/#sec-modulenamespacecreate):

> Let `sortedExports` be a new List containing the same values as the list exports where the values are ordered as if an Array of the same values had been sorted using `Array.prototype.sort` using `undefined` as `comparefn`.