dillon1000/react

[valueblocks] Update some passes to use the new visitor

Updates some passes from ReactiveScopes/ to use the visitor added in the 
previous PR. The +124/-354 line count on this diff tells the story  — the new 
visitor avoids a lot of boilerplate and helps focus on the logic not the 
traversal. 

Note that there are a few passes which transform the function such as 
adding/removing scopes. A follow-up will extend the visitor to support that and 
convert the remaining passes.