[stdlib] Substring: Restore original Range paths
[stdlib] Substring: Restore original Range paths

This eliminates a couple of _debugPreconditions which seem to change inlining enough to interfere with some benchmarks.

benlangmuir/swift,tkremenek/swift,parkera/swift,jmgc/swift,rudkx/swift,atrick/swift,ahoppen/swift,hooman/swift,atrick/swift,parkera/swift,apple/swift,rudkx/swift,tkremenek/swift,hooman/swift,hooman/swift,gregomni/swift,ahoppen/swift,parkera/swift,roambotics/swift,tkremenek/swift,rudkx/swift,glessard/swift,xwu/swift,apple/swift,gregomni/swift,roambotics/swift,glessard/swift,JGiola/swift,gregomni/swift,rudkx/swift,xwu/swift,jmgc/swift,apple/swift,ahoppen/swift,benlangmuir/swift,tkremenek/swift,apple/swift,JGiola/swift,jmgc/swift,jmgc/swift,atrick/swift,gregomni/swift,apple/swift,hooman/swift,parkera/swift,tkremenek/swift,jmgc/swift,hooman/swift,atrick/swift,roambotics/swift,atrick/swift,benlangmuir/swift,benlangmuir/swift,jmgc/swift,hooman/swift,roambotics/swift,glessard/swift,benlangmuir/swift,JGiola/swift,xwu/swift,gregomni/swift,glessard/swift,parkera/swift,tkremenek/swift,benlangmuir/swift,ahoppen/swift,hooman/swift,xwu/swift,xwu/swift,roambotics/swift,glessard/swift,parkera/swift,rudkx/swift,xwu/swift,ahoppen/swift,jmgc/swift,JGiola/swift,rudkx/swift,gregomni/swift,glessard/swift,JGiola/swift,apple/swift,JGiola/swift,roambotics/swift,xwu/swift,atrick/swift,parkera/swift,ahoppen/swift,parkera/swift,tkremenek/swift