Currently, every time we call a JS function on a Scope, the Scope reregisters itself on the OperationContext, and then deregisters itself before returning. In a typical query this might happen many times on the same OperationContext. It seems like it would be simpler to only register/deregister once.

We have a similar mechanism already, called reattachToOperationContext() / detachFromOperationContext(), so let's try using that hook to register and deregister the Scope as well.