Check return types when returning inside try-finally

Summary: Adds a VerifyRetType{C,V} for finally trampoline.

Fixes #3998

Reviewed By: @JoelMarcey

Differential Revision: D1660033

Signature: t1:1660033:1415294884:3426c5634ca6a09f8fcf74a2b50943ae8e1ac52b