Factor out mapping an operand to a parameter index. NFC.
Factor out mapping an operand to a parameter index. NFC.

Swift SVN r15717

hughbe/swift,danielmartin/swift,bitjammer/swift,sschiau/swift,shajrawi/swift,atrick/swift,dduan/swift,parkera/swift,frootloops/swift,tkremenek/swift,gribozavr/swift,emilstahl/swift,ahoppen/swift,tkremenek/swift,airspeedswift/swift,xedin/swift,glessard/swift,deyton/swift,gmilos/swift,ken0nek/swift,brentdax/swift,jckarter/swift,kentya6/swift,bitjammer/swift,devincoughlin/swift,return/swift,ahoppen/swift,therealbnut/swift,karwa/swift,atrick/swift,danielmartin/swift,kperryua/swift,tjw/swift,apple/swift,shahmishal/swift,devincoughlin/swift,swiftix/swift.old,rudkx/swift,deyton/swift,codestergit/swift,uasys/swift,emilstahl/swift,shahmishal/swift,JaSpa/swift,parkera/swift,jtbandes/swift,karwa/swift,Jnosh/swift,khizkhiz/swift,ken0nek/swift,codestergit/swift,swiftix/swift.old,modocache/swift,frootloops/swift,mightydeveloper/swift,kusl/swift,LeoShimonaka/swift,amraboelela/swift,shajrawi/swift,ken0nek/swift,sschiau/swift,milseman/swift,zisko/swift,gmilos/swift,austinzheng/swift,gottesmm/swift,gribozavr/swift,mightydeveloper/swift,return/swift,jtbandes/swift,rudkx/swift,jopamer/swift,hooman/swift,bitjammer/swift,shajrawi/swift,allevato/swift,calebd/swift,harlanhaskins/swift,zisko/swift,adrfer/swift,JaSpa/swift,johnno1962d/swift,aschwaighofer/swift,felix91gr/swift,adrfer/swift,benlangmuir/swift,gmilos/swift,IngmarStein/swift,zisko/swift,sdulal/swift,nathawes/swift,nathawes/swift,cbrentharris/swift,jckarter/swift,adrfer/swift,huonw/swift,sdulal/swift,codestergit/swift,kstaring/swift,hughbe/swift,therealbnut/swift,zisko/swift,Ivacker/swift,CodaFi/swift,MukeshKumarS/Swift,tkremenek/swift,devincoughlin/swift,johnno1962d/swift,lorentey/swift,MukeshKumarS/Swift,stephentyrone/swift,alblue/swift,return/swift,mightydeveloper/swift,lorentey/swift,arvedviehweger/swift,return/swift,OscarSwanros/swift,CodaFi/swift,ken0nek/swift,jopamer/swift,swiftix/swift.old,tjw/swift,Jnosh/swift,JGiola/swift,parkera/swift,shajrawi/swift,russbishop/swift,milseman/swift,shajrawi/swift,kusl/swift,jmgc/swift,airspeedswift/swift,uasys/swift,zisko/swift,russbishop/swift,harlanhaskins/swift,cbrentharris/swift,devincoughlin/swift,gregomni/swift,OscarSwanros/swift,frootloops/swift,hooman/swift,deyton/swift,shahmishal/swift,bitjammer/swift,emilstahl/swift,benlangmuir/swift,stephentyrone/swift,milseman/swift,glessard/swift,arvedviehweger/swift,jckarter/swift,deyton/swift,manavgabhawala/swift,natecook1000/swift,harlanhaskins/swift,austinzheng/swift,modocache/swift,parkera/swift,uasys/swift,jopamer/swift,sdulal/swift,stephentyrone/swift,roambotics/swift,brentdax/swift,KrishMunot/swift,xedin/swift,xwu/swift,hooman/swift,tardieu/swift,gregomni/swift,shajrawi/swift,practicalswift/swift,Ivacker/swift,slavapestov/swift,return/swift,JaSpa/swift,adrfer/swift,natecook1000/swift,xwu/swift,IngmarStein/swift,tkremenek/swift,swiftix/swift.old,gregomni/swift,Jnosh/swift,dduan/swift,felix91gr/swift,rudkx/swift,tardieu/swift,hooman/swift,practicalswift/swift,nathawes/swift,ahoppen/swift,mightydeveloper/swift,tardieu/swift,jmgc/swift,jmgc/swift,swiftix/swift,slavapestov/swift,Ivacker/swift,nathawes/swift,jopamer/swift,apple/swift,milseman/swift,roambotics/swift,calebd/swift,gribozavr/swift,lorentey/swift,jmgc/swift,frootloops/swift,LeoShimonaka/swift,johnno1962d/swift,xedin/swift,glessard/swift,LeoShimonaka/swift,hooman/swift,russbishop/swift,sdulal/swift,dreamsxin/swift,huonw/swift,shahmishal/swift,swiftix/swift,roambotics/swift,dduan/swift,kentya6/swift,shajrawi/swift,austinzheng/swift,khizkhiz/swift,tinysun212/swift-windows,jopamer/swift,LeoShimonaka/swift,MukeshKumarS/Swift,Jnosh/swift,IngmarStein/swift,swiftix/swift.old,bitjammer/swift,arvedviehweger/swift,nathawes/swift,hughbe/swift,Jnosh/swift,gribozavr/swift,amraboelela/swift,OscarSwanros/swift,johnno1962d/swift,slavapestov/swift,kentya6/swift,ken0nek/swift,brentdax/swift,devincoughlin/swift,SwiftAndroid/swift,tjw/swift,atrick/swift,johnno1962d/swift,LeoShimonaka/swift,gottesmm/swift,austinzheng/swift,SwiftAndroid/swift,MukeshKumarS/Swift,khizkhiz/swift,jtbandes/swift,tjw/swift,lorentey/swift,kperryua/swift,dduan/swift,alblue/swift,ben-ng/swift,devincoughlin/swift,modocache/swift,sschiau/swift,shahmishal/swift,gribozavr/swift,kperryua/swift,karwa/swift,apple/swift,kstaring/swift,MukeshKumarS/Swift,mightydeveloper/swift,arvedviehweger/swift,shajrawi/swift,shahmishal/swift,kperryua/swift,manavgabhawala/swift,Jnosh/swift,calebd/swift,IngmarStein/swift,tkremenek/swift,amraboelela/swift,stephentyrone/swift,CodaFi/swift,djwbrown/swift,CodaFi/swift,tjw/swift,MukeshKumarS/Swift,emilstahl/swift,aschwaighofer/swift,LeoShimonaka/swift,CodaFi/swift,sschiau/swift,jckarter/swift,slavapestov/swift,JGiola/swift,emilstahl/swift,tardieu/swift,milseman/swift,uasys/swift,calebd/swift,Jnosh/swift,codestergit/swift,practicalswift/swift,djwbrown/swift,KrishMunot/swift,practicalswift/swift,gottesmm/swift,jtbandes/swift,felix91gr/swift,allevato/swift,KrishMunot/swift,jopamer/swift,sschiau/swift,tinysun212/swift-windows,cbrentharris/swift,arvedviehweger/swift,zisko/swift,swiftix/swift.old,dreamsxin/swift,swiftix/swift,manavgabhawala/swift,calebd/swift,cbrentharris/swift,KrishMunot/swift,kusl/swift,deyton/swift,adrfer/swift,ben-ng/swift,swiftix/swift,roambotics/swift,KrishMunot/swift,dduan/swift,allevato/swift,airspeedswift/swift,kstaring/swift,karwa/swift,uasys/swift,huonw/swift,alblue/swift,huonw/swift,felix91gr/swift,slavapestov/swift,IngmarStein/swift,russbishop/swift,jtbandes/swift,sschiau/swift,hughbe/swift,SwiftAndroid/swift,jmgc/swift,SwiftAndroid/swift,apple/swift,benlangmuir/swift,kusl/swift,karwa/swift,OscarSwanros/swift,kperryua/swift,tkremenek/swift,kperryua/swift,stephentyrone/swift,shahmishal/swift,JGiola/swift,gribozavr/swift,khizkhiz/swift,jtbandes/swift,arvedviehweger/swift,practicalswift/swift,frootloops/swift,kentya6/swift,SwiftAndroid/swift,alblue/swift,djwbrown/swift,stephentyrone/swift,KrishMunot/swift,airspeedswift/swift,JaSpa/swift,ben-ng/swift,swiftix/swift.old,amraboelela/swift,kperryua/swift,kentya6/swift,xedin/swift,CodaFi/swift,gottesmm/swift,djwbrown/swift,tjw/swift,ahoppen/swift,swiftix/swift,brentdax/swift,bitjammer/swift,austinzheng/swift,gottesmm/swift,LeoShimonaka/swift,alblue/swift,zisko/swift,bitjammer/swift,dduan/swift,karwa/swift,tjw/swift,glessard/swift,hooman/swift,lorentey/swift,emilstahl/swift,johnno1962d/swift,arvedviehweger/swift,return/swift,jckarter/swift,hughbe/swift,practicalswift/swift,uasys/swift,benlangmuir/swift,devincoughlin/swift,glessard/swift,amraboelela/swift,khizkhiz/swift,tardieu/swift,hooman/swift,gribozavr/swift,JGiola/swift,OscarSwanros/swift,modocache/swift,kstaring/swift,brentdax/swift,aschwaighofer/swift,parkera/swift,gmilos/swift,ken0nek/swift,benlangmuir/swift,ben-ng/swift,deyton/swift,JaSpa/swift,jmgc/swift,russbishop/swift,manavgabhawala/swift,JGiola/swift,uasys/swift,sschiau/swift,kusl/swift,cbrentharris/swift,felix91gr/swift,jopamer/swift,natecook1000/swift,SwiftAndroid/swift,tinysun212/swift-windows,modocache/swift,gribozavr/swift,ahoppen/swift,huonw/swift,OscarSwanros/swift,Ivacker/swift,sdulal/swift,xedin/swift,gregomni/swift,cbrentharris/swift,MukeshKumarS/Swift,emilstahl/swift,aschwaighofer/swift,karwa/swift,aschwaighofer/swift,hughbe/swift,rudkx/swift,jckarter/swift,jtbandes/swift,Ivacker/swift,CodaFi/swift,harlanhaskins/swift,gmilos/swift,dduan/swift,rudkx/swift,kstaring/swift,harlanhaskins/swift,danielmartin/swift,lorentey/swift,parkera/swift,cbrentharris/swift,modocache/swift,milseman/swift,kstaring/swift,brentdax/swift,xedin/swift,manavgabhawala/swift,natecook1000/swift,calebd/swift,glessard/swift,benlangmuir/swift,alblue/swift,stephentyrone/swift,felix91gr/swift,djwbrown/swift,nathawes/swift,ben-ng/swift,adrfer/swift,kentya6/swift,codestergit/swift,djwbrown/swift,therealbnut/swift,SwiftAndroid/swift,tinysun212/swift-windows,xwu/swift,amraboelela/swift,frootloops/swift,swiftix/swift,kstaring/swift,austinzheng/swift,modocache/swift,johnno1962d/swift,therealbnut/swift,deyton/swift,KrishMunot/swift,gmilos/swift,practicalswift/swift,tinysun212/swift-windows,Ivacker/swift,aschwaighofer/swift,parkera/swift,amraboelela/swift,alblue/swift,jmgc/swift,mightydeveloper/swift,natecook1000/swift,harlanhaskins/swift,xwu/swift,manavgabhawala/swift,tinysun212/swift-windows,xedin/swift,airspeedswift/swift,sdulal/swift,frootloops/swift,adrfer/swift,xedin/swift,mightydeveloper/swift,return/swift,gmilos/swift,atrick/swift,gottesmm/swift,manavgabhawala/swift,tardieu/swift,tinysun212/swift-windows,milseman/swift,kentya6/swift,allevato/swift,huonw/swift,JGiola/swift,kusl/swift,therealbnut/swift,xwu/swift,kentya6/swift,codestergit/swift,IngmarStein/swift,djwbrown/swift,IngmarStein/swift,natecook1000/swift,kusl/swift,slavapestov/swift,atrick/swift,tkremenek/swift,austinzheng/swift,OscarSwanros/swift,danielmartin/swift,LeoShimonaka/swift,mightydeveloper/swift,roambotics/swift,karwa/swift,emilstahl/swift,danielmartin/swift,russbishop/swift,Ivacker/swift,airspeedswift/swift,sschiau/swift,xwu/swift,therealbnut/swift,devincoughlin/swift,natecook1000/swift,felix91gr/swift,khizkhiz/swift,apple/swift,gregomni/swift,calebd/swift,cbrentharris/swift,allevato/swift,tardieu/swift,JaSpa/swift,nathawes/swift,swiftix/swift,brentdax/swift,atrick/swift,roambotics/swift,ahoppen/swift,Ivacker/swift,swiftix/swift.old,JaSpa/swift,ben-ng/swift,danielmartin/swift,lorentey/swift,russbishop/swift,khizkhiz/swift,aschwaighofer/swift,shahmishal/swift,apple/swift,gottesmm/swift,gregomni/swift,rudkx/swift,practicalswift/swift,sdulal/swift,ken0nek/swift,slavapestov/swift,allevato/swift,xwu/swift,ben-ng/swift,danielmartin/swift,airspeedswift/swift,allevato/swift,sdulal/swift,therealbnut/swift,lorentey/swift,huonw/swift,codestergit/swift,kusl/swift,harlanhaskins/swift,parkera/swift,jckarter/swift,hughbe/swift