IRGen: Add some paranoia assertions to ensure emitObjCPropertyMethodDescriptors is consistent with var and subscript decls.
IRGen: Add some paranoia assertions to ensure emitObjCPropertyMethodDescriptors is consistent with var and subscript decls.

Suggested in review by GregP.

Swift SVN r20522

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