I think we may be having a terminology issue here: you seem to define "prototype based" languages as those that have dictionaries for instance variables and methods, whereas class based languages have structs for instance variables and compile-time generated vtables for dispatch.

But this looks like an implementation detail that does not seem related to prototypes vs classes, but more to dynamic vs static ones (e.g. Cecil does prototypes without storing a dictionary in the object, while ruby does classes with dictionaries)

So we may be in agreement, but referring to different things.