Update comments and simplify some code in the devirtualizer.
Update comments and simplify some code in the devirtualizer.

More prep for refactoring into utility functions that can be used
outside of the devirtualization pass.

Swift SVN r25671

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