swift234

[Type checker] Make sure that the omit-needless-words logic validates decls.

With the introduction of near-miss checking for optional @objc
protocol requirements, the omit-needless-words logic within the type
checker started being applied to arbitrary declarations that might not
have been type-checked, leading to crashes in various multi-file
scenarios that I wasn't able to reduce down to a sensible test
case. Make sure these declarations get type-checked, fixing
rdar://problem/26413181.