Extensible is only defined on ordinary object

[Jack-Works]

O is an object, not an ordinary object, so you cannot access O.[[Extensible]] directly.

If O.[[Extensible]] is false, throw a TypeError exception.

What should it behave for the exotic objects? Calling O.IsExtensible() might trigger user code (in a Proxy).

[Jack-Works]

Hi you also need to change ! to ? in https://tc39.es/ecma262/#_ref_8028 (ClassDefinitionEvaluation)

[mhofman]

Hi you also need to change ! to ? in https://tc39.es/ecma262/#_ref_8028 (ClassDefinitionEvaluation)

You're correct! While afaict F in that AO is guaranteed to not be exotic, static element evaluations can make F non-extensible, which would result in PrivateMethodOrAccessorAdd now throwing.

This is however independent of this change. We need a test for that.

After all, I don't think that operation can result in an abrupt completion. See #9

[erights]

Reopening, thanks!