We should propose harden to tc39, together with whatever other primitive hardening/freezing/snapshotting primitives we need to cover our needs, including those of tc53 and Moddable.

Should we propose that properties made non-writable,non-configurable by harden also act as if the override mistake were absent? As we've seen, shimming this everywhere with accessors is expensive. But done via a standard mechanism, the platform could fix this cheaply.

Note: There was already an attempt to just fix the override mistake in the language itself. That failed under testing --- a little old code was incompatible with fixing this, but enough code that no one was willing to ratify it. The best we can get is probably that new hardening/freezing/snapshotting mechanisms fix this. Since these mechanisms would be new, the fix would effectively be opt-in and not break old code.