Rework scope info updating in block-scoping transform
Rework scope info updating in block-scoping transform

I previously tried an approach to scope bindings from var to scope but
it didn't catch all cases. This is evident in this bug:

https://phabricator.babeljs.io/T2892

Where even after transforming a const to a var we still get an error
that it's read-only.

This approach will go through and delete every existing let and const
binding and creates a new one with the kind "var"

forivall/tacoscript,forivall/tacoscript