dillon1000/react

Propagate reactive scope dependencies transitively

During PruneNonReactiveDependencies, we sometimes need to promote a value from 
non-reactive to reactive if it ended up being grouped in the same reactive scope 
as some other reactive value. This generally happens due to interleaving 
mutations. 

In this case all downstream usage of the promoted value need to also be 
considered reactive. Fully propagating the reactivity requires re-running 
InferReactivePlaces, to account for things like control reactivity. We can't yet 
reuse that pass here though, because we haven't unified the pipeline on HIR yet. 

For now, we propagate the reactivity through local variables and downstream 
reactive scopes. See test fixtures for some examples that now correctly 
propagate reactivity and some that need the full reactivity inference to run 
correctly. The latter cases are handled in the next PR.