dillon1000/react

PropagateScopeDeps uses visitor infra

PropagateScopeDependencies is one of the few places we don't use the new visitor 
infra for traversing ReactiveFunction. Or rather it _was_! 

Note that there's a bit less value here than in other places since we have to 
handle each terminal variant with custom logic, but at least it's more 
consistent with the rest of the codebase now.