The resilient methods will all be keyed by their dispatch thunks, so for methods of local subclasses, we can use the offsets relative to the dynamic base as identifiers without having to adjust for that dynamic base.
Client code doesn't necessarily know the dispatch table indexes (and in time, there may not even be such a thing), and the dispatch thunk is a stable ABI artifact that can reliably uniquely identify the thing.
This is a bit easier than the fully general case where both the external descriptor and local pattern have captured arguments (because of generics or subscript indices) since we don't have to combine the two argument files in one component.
