Each evaluation of a class declared inside a function creates fresh
private names, while the compiled class shares one layout across
evaluations, so any private member refused the class. undici's webidl
createIterator declares such a class (FastIterableIterator) at module load.
The two agree when every private name is used only on `this` inside the
class's own instance members (`this.#x`, `#x in this`), never inside a
nested class or non-arrow function, and the class has no static members:
each instance then meets only the methods of its own evaluation. Those
classes now compile; everything else keeps the refusal.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
