Remove the witness_method instruction during devirtualization.
Remove the witness_method instruction during devirtualization.

If we have a witness_method that has no uses after removing the apply
that we've just devirtualized, then remove the witness_method as well.

Some small renaming as well, to be consistent with other functions.

Swift SVN r26342

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