let/const renaming doesn't accurately reflect the "temporal dead-zone"

Created by: natefaubion

In lastest node:

"use strict";
function foo() {
  console.log(a);
}
let a = 12;
foo();

In latest sjs:

'use strict';
function foo$274() {
    console.log(a);
}
let a$275 = 12;
foo$274();

For let and const we just push a new Rename on to the context of any following syntax (which I suppose would be considered a "lexical window"). I think we can actually just treat it like we treat var and add it to the definition context, and defer to the runtime to check for the dead-zone.