Fix a warning: implicit conversion of nullptr constant to 'bool'
Fix a warning: implicit conversion of nullptr constant to 'bool'

Swift SVN r25543

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