Provide a way to eagerly marshal (snapshot) all properties to js object.

[reitowo]

When a function returns a class object, it can't be serialized to json and send it across RPC, because all of properties are dynamically loaded. Is there any way to marshal it to a completely JS object? Because compiling into a module doesn't work well.

It will be nice if can provide a snapshot helper to take the snapshot of a reference and let it pass with rpc.