Update a comment and make arguments more explicit. rdar://problem/15493512.
Update a comment and make arguments more explicit.
rdar://problem/15493512.

Swift SVN r14788

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