class [Symbol.iterator] methods: super[Symbol.iterator]() recurses; delete C.prototype[Symbol.iterator] is a no-op #11698

Found while fixing #11692 (PR #11697). Both reproduce on pristine main 6a50907 and are unrelated to that fix.

1. super[Symbol.iterator]() recurses until the stack overflows

class B { *[Symbol.iterator]() { yield 1; yield 2; } }
class D extends B { [Symbol.iterator]() { return super[Symbol.iterator](); } }
console.log([...new D()]); // node: [ 1, 2 ]; perry: stack overflow

2. delete C.prototype[Symbol.iterator] doesn't remove the method

class C { *[Symbol.iterator]() { yield 1; } }
delete (C.prototype as any)[Symbol.iterator];
console.log(Symbol.iterator in new C()); // node: false; perry: true

Likely cause: symbol-keyed class methods are dispatched under internal names (@@iterator) and stored under the symbol key. super lookup and delete don't resolve that mapping the same way the call path does.