Add Regression Tests for Bogus Existential Checked Casts
Add Regression Tests for Bogus Existential Checked Casts

Try to make sure we don't do the wrong thing here in the future.  We've
been accepting the optional code for a long long time.

See rdar://57674858

jmgc/swift,CodaFi/swift,parkera/swift,apple/swift,lorentey/swift,atrick/swift,tkremenek/swift,karwa/swift,jmgc/swift,nathawes/swift,tkremenek/swift,karwa/swift,jmgc/swift,aschwaighofer/swift,karwa/swift,parkera/swift,JGiola/swift,benlangmuir/swift,parkera/swift,stephentyrone/swift,apple/swift,ahoppen/swift,allevato/swift,airspeedswift/swift,karwa/swift,tkremenek/swift,jckarter/swift,karwa/swift,allevato/swift,stephentyrone/swift,allevato/swift,aschwaighofer/swift,hooman/swift,harlanhaskins/swift,airspeedswift/swift,parkera/swift,benlangmuir/swift,xwu/swift,tkremenek/swift,stephentyrone/swift,stephentyrone/swift,CodaFi/swift,harlanhaskins/swift,karwa/swift,lorentey/swift,CodaFi/swift,benlangmuir/swift,karwa/swift,gribozavr/swift,gregomni/swift,gribozavr/swift,rudkx/swift,harlanhaskins/swift,tkremenek/swift,apple/swift,gribozavr/swift,ahoppen/swift,roambotics/swift,allevato/swift,nathawes/swift,airspeedswift/swift,apple/swift,lorentey/swift,CodaFi/swift,nathawes/swift,rudkx/swift,jckarter/swift,JGiola/swift,roambotics/swift,JGiola/swift,lorentey/swift,allevato/swift,rudkx/swift,harlanhaskins/swift,stephentyrone/swift,tkremenek/swift,airspeedswift/swift,benlangmuir/swift,glessard/swift,ahoppen/swift,glessard/swift,harlanhaskins/swift,apple/swift,atrick/swift,roambotics/swift,CodaFi/swift,gribozavr/swift,ahoppen/swift,atrick/swift,gribozavr/swift,benlangmuir/swift,hooman/swift,jckarter/swift,aschwaighofer/swift,jmgc/swift,harlanhaskins/swift,roambotics/swift,gribozavr/swift,nathawes/swift,aschwaighofer/swift,jckarter/swift,glessard/swift,ahoppen/swift,stephentyrone/swift,JGiola/swift,glessard/swift,lorentey/swift,glessard/swift,parkera/swift,airspeedswift/swift,parkera/swift,JGiola/swift,parkera/swift,stephentyrone/swift,atrick/swift,xwu/swift,CodaFi/swift,nathawes/swift,rudkx/swift,xwu/swift,gregomni/swift,apple/swift,roambotics/swift,aschwaighofer/swift,harlanhaskins/swift,gregomni/swift,xwu/swift,jmgc/swift,hooman/swift,tkremenek/swift,ahoppen/swift,jckarter/swift,lorentey/swift,jmgc/swift,xwu/swift,roambotics/swift,rudkx/swift,nathawes/swift,airspeedswift/swift,JGiola/swift,gregomni/swift,hooman/swift,lorentey/swift,jckarter/swift,jckarter/swift,karwa/swift,nathawes/swift,gribozavr/swift,xwu/swift,aschwaighofer/swift,hooman/swift,gregomni/swift,atrick/swift,lorentey/swift,CodaFi/swift,hooman/swift,parkera/swift,gregomni/swift,airspeedswift/swift,hooman/swift,jmgc/swift,glessard/swift,atrick/swift,allevato/swift,allevato/swift,xwu/swift,aschwaighofer/swift,rudkx/swift,benlangmuir/swift,gribozavr/swift