[CSSimplify] Replace `locatorEndsWith` with `isLastElement` accessor
[CSSimplify] Replace `locatorEndsWith` with `isLastElement` accessor

benlangmuir/swift,glessard/swift,glessard/swift,benlangmuir/swift,glessard/swift,apple/swift,apple/swift,roambotics/swift,benlangmuir/swift,apple/swift,roambotics/swift,roambotics/swift,roambotics/swift,benlangmuir/swift,benlangmuir/swift,apple/swift,benlangmuir/swift,roambotics/swift,apple/swift,glessard/swift,glessard/swift,glessard/swift,apple/swift,roambotics/swift