[TypeChecker/Constness] Diagnostics: Walk into multi-statement closures when inference is enabled
[TypeChecker/Constness] Diagnostics: Walk into multi-statement closures when inference is enabled

When multi-statement closure inference is enabled it's body is
type-checked together with enclosing context, so they could be
walked directly just like single-expressions ones.

ahoppen/swift,glessard/swift,rudkx/swift,JGiola/swift,gregomni/swift,glessard/swift,ahoppen/swift,JGiola/swift,atrick/swift,gregomni/swift,gregomni/swift,apple/swift,atrick/swift,JGiola/swift,gregomni/swift,apple/swift,atrick/swift,atrick/swift,JGiola/swift,benlangmuir/swift,benlangmuir/swift,apple/swift,roambotics/swift,roambotics/swift,ahoppen/swift,roambotics/swift,roambotics/swift,benlangmuir/swift,roambotics/swift,benlangmuir/swift,atrick/swift,atrick/swift,rudkx/swift,glessard/swift,JGiola/swift,apple/swift,JGiola/swift,glessard/swift,gregomni/swift,roambotics/swift,rudkx/swift,ahoppen/swift,glessard/swift,ahoppen/swift,rudkx/swift,gregomni/swift,benlangmuir/swift,glessard/swift,ahoppen/swift,apple/swift,rudkx/swift,apple/swift,benlangmuir/swift,rudkx/swift