Closure in a block can't see a binding declared later in the same block (ReferenceError) #11778

Inside a plain { } block, a closure that refers to a const/let/class declared later in the same block throws a ReferenceError when it runs after that declaration. Node runs it fine. The same code at top level works in perry.

{
  const f = () => g;
  const g = 5;
  console.log(f());   // node: 5   perry: ReferenceError: g is not defined
}

It's the same with a class declared later in the block ({ const f = () => new SC(); class SC {} f(); } gives ReferenceError: SC is not defined). This was found while working on #11777 and reproduces on main before that change (6a61c2ceff), so it's not caused by #11777. It looks related to closed #6523. Probes are in secret-tests scratchpad/class-super/fw2.ts and fw3.ts.