Fix: Unexpect action when declare variables in switch-case (fixes #1453)

When declare variables in case statement and use it after, block-scoped-var will report an error  "xxx used outside of binding context".

See #1453.
But block-scoped-var can't collect variables declare in switch-case. My code just work on it. Is there any better way to fix it?

ping the author @mduvall.