[AST] Don't crash when dumping a function type that doesn't have extInfo
[AST] Don't crash when dumping a function type that doesn't have extInfo

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