SIL: Add a couple of assertions
SIL: Add a couple of assertions

These were helpful while debugging <rdar://problem/31163470>.

tjw/swift,CodaFi/swift,natecook1000/swift,austinzheng/swift,brentdax/swift,gregomni/swift,jckarter/swift,amraboelela/swift,airspeedswift/swift,nathawes/swift,stephentyrone/swift,tkremenek/swift,CodaFi/swift,roambotics/swift,jckarter/swift,allevato/swift,djwbrown/swift,ahoppen/swift,apple/swift,zisko/swift,sschiau/swift,Jnosh/swift,uasys/swift,huonw/swift,calebd/swift,apple/swift,huonw/swift,deyton/swift,sschiau/swift,xedin/swift,felix91gr/swift,gribozavr/swift,jopamer/swift,zisko/swift,sschiau/swift,tinysun212/swift-windows,hooman/swift,JGiola/swift,jtbandes/swift,parkera/swift,uasys/swift,frootloops/swift,xedin/swift,lorentey/swift,aschwaighofer/swift,arvedviehweger/swift,zisko/swift,gribozavr/swift,return/swift,rudkx/swift,airspeedswift/swift,danielmartin/swift,jckarter/swift,calebd/swift,rudkx/swift,djwbrown/swift,aschwaighofer/swift,allevato/swift,shahmishal/swift,OscarSwanros/swift,shajrawi/swift,bitjammer/swift,atrick/swift,JGiola/swift,OscarSwanros/swift,huonw/swift,milseman/swift,aschwaighofer/swift,hooman/swift,jmgc/swift,hughbe/swift,bitjammer/swift,brentdax/swift,gribozavr/swift,shajrawi/swift,natecook1000/swift,austinzheng/swift,parkera/swift,deyton/swift,hughbe/swift,karwa/swift,hooman/swift,jopamer/swift,milseman/swift,gribozavr/swift,milseman/swift,nathawes/swift,zisko/swift,return/swift,amraboelela/swift,xedin/swift,brentdax/swift,djwbrown/swift,harlanhaskins/swift,practicalswift/swift,atrick/swift,shajrawi/swift,apple/swift,allevato/swift,tjw/swift,practicalswift/swift,airspeedswift/swift,airspeedswift/swift,arvedviehweger/swift,karwa/swift,jmgc/swift,deyton/swift,swiftix/swift,devincoughlin/swift,milseman/swift,karwa/swift,tjw/swift,hughbe/swift,Jnosh/swift,tinysun212/swift-windows,lorentey/swift,frootloops/swift,bitjammer/swift,tjw/swift,karwa/swift,codestergit/swift,natecook1000/swift,natecook1000/swift,JGiola/swift,roambotics/swift,OscarSwanros/swift,frootloops/swift,jopamer/swift,codestergit/swift,airspeedswift/swift,swiftix/swift,codestergit/swift,jopamer/swift,felix91gr/swift,alblue/swift,roambotics/swift,CodaFi/swift,tjw/swift,aschwaighofer/swift,amraboelela/swift,sschiau/swift,djwbrown/swift,apple/swift,xwu/swift,xedin/swift,bitjammer/swift,jtbandes/swift,jopamer/swift,jopamer/swift,alblue/swift,shahmishal/swift,bitjammer/swift,calebd/swift,jtbandes/swift,gribozavr/swift,OscarSwanros/swift,harlanhaskins/swift,tinysun212/swift-windows,practicalswift/swift,arvedviehweger/swift,benlangmuir/swift,codestergit/swift,austinzheng/swift,felix91gr/swift,return/swift,ahoppen/swift,natecook1000/swift,milseman/swift,frootloops/swift,harlanhaskins/swift,danielmartin/swift,stephentyrone/swift,djwbrown/swift,glessard/swift,benlangmuir/swift,Jnosh/swift,JGiola/swift,arvedviehweger/swift,gregomni/swift,alblue/swift,alblue/swift,return/swift,practicalswift/swift,djwbrown/swift,deyton/swift,swiftix/swift,deyton/swift,tinysun212/swift-windows,tkremenek/swift,return/swift,jtbandes/swift,allevato/swift,xedin/swift,rudkx/swift,devincoughlin/swift,hughbe/swift,karwa/swift,calebd/swift,karwa/swift,swiftix/swift,benlangmuir/swift,tinysun212/swift-windows,aschwaighofer/swift,gribozavr/swift,xedin/swift,amraboelela/swift,airspeedswift/swift,jckarter/swift,stephentyrone/swift,ahoppen/swift,austinzheng/swift,stephentyrone/swift,practicalswift/swift,felix91gr/swift,glessard/swift,JGiola/swift,hughbe/swift,uasys/swift,zisko/swift,xwu/swift,lorentey/swift,calebd/swift,hooman/swift,codestergit/swift,frootloops/swift,glessard/swift,sschiau/swift,CodaFi/swift,hooman/swift,allevato/swift,benlangmuir/swift,deyton/swift,tkremenek/swift,rudkx/swift,jopamer/swift,shahmishal/swift,codestergit/swift,xwu/swift,jmgc/swift,harlanhaskins/swift,devincoughlin/swift,gregomni/swift,hooman/swift,milseman/swift,arvedviehweger/swift,xwu/swift,xedin/swift,Jnosh/swift,shajrawi/swift,codestergit/swift,huonw/swift,alblue/swift,jtbandes/swift,ahoppen/swift,airspeedswift/swift,atrick/swift,hooman/swift,sschiau/swift,nathawes/swift,apple/swift,brentdax/swift,nathawes/swift,amraboelela/swift,bitjammer/swift,devincoughlin/swift,huonw/swift,uasys/swift,stephentyrone/swift,stephentyrone/swift,parkera/swift,benlangmuir/swift,tjw/swift,shajrawi/swift,bitjammer/swift,parkera/swift,glessard/swift,jckarter/swift,sschiau/swift,huonw/swift,lorentey/swift,tinysun212/swift-windows,karwa/swift,danielmartin/swift,devincoughlin/swift,roambotics/swift,austinzheng/swift,return/swift,arvedviehweger/swift,felix91gr/swift,roambotics/swift,CodaFi/swift,tkremenek/swift,return/swift,atrick/swift,harlanhaskins/swift,frootloops/swift,nathawes/swift,natecook1000/swift,jmgc/swift,danielmartin/swift,xedin/swift,lorentey/swift,devincoughlin/swift,djwbrown/swift,tkremenek/swift,parkera/swift,glessard/swift,shahmishal/swift,aschwaighofer/swift,jtbandes/swift,zisko/swift,uasys/swift,atrick/swift,huonw/swift,allevato/swift,danielmartin/swift,jckarter/swift,OscarSwanros/swift,lorentey/swift,milseman/swift,tjw/swift,brentdax/swift,lorentey/swift,practicalswift/swift,hughbe/swift,jmgc/swift,shajrawi/swift,stephentyrone/swift,Jnosh/swift,austinzheng/swift,practicalswift/swift,calebd/swift,practicalswift/swift,Jnosh/swift,OscarSwanros/swift,jckarter/swift,danielmartin/swift,nathawes/swift,gregomni/swift,zisko/swift,xwu/swift,JGiola/swift,allevato/swift,benlangmuir/swift,jtbandes/swift,tkremenek/swift,xwu/swift,glessard/swift,rudkx/swift,alblue/swift,hughbe/swift,shajrawi/swift,brentdax/swift,amraboelela/swift,tinysun212/swift-windows,shajrawi/swift,Jnosh/swift,jmgc/swift,swiftix/swift,ahoppen/swift,gribozavr/swift,shahmishal/swift,karwa/swift,rudkx/swift,calebd/swift,tkremenek/swift,ahoppen/swift,swiftix/swift,uasys/swift,aschwaighofer/swift,nathawes/swift,lorentey/swift,brentdax/swift,shahmishal/swift,parkera/swift,parkera/swift,shahmishal/swift,deyton/swift,devincoughlin/swift,roambotics/swift,CodaFi/swift,uasys/swift,parkera/swift,austinzheng/swift,frootloops/swift,harlanhaskins/swift,jmgc/swift,arvedviehweger/swift,felix91gr/swift,OscarSwanros/swift,CodaFi/swift,atrick/swift,felix91gr/swift,sschiau/swift,gregomni/swift,amraboelela/swift,alblue/swift,shahmishal/swift,harlanhaskins/swift,apple/swift,gregomni/swift,gribozavr/swift,xwu/swift,danielmartin/swift,swiftix/swift,natecook1000/swift,devincoughlin/swift