[Test] Add a test case for extension where clause with missing body
[Test] Add a test case for extension where clause with missing body

rdar://problem/66943328

rudkx/swift,JGiola/swift,CodaFi/swift,JGiola/swift,jmgc/swift,nathawes/swift,tkremenek/swift,atrick/swift,tkremenek/swift,apple/swift,atrick/swift,xwu/swift,glessard/swift,JGiola/swift,benlangmuir/swift,benlangmuir/swift,parkera/swift,ahoppen/swift,CodaFi/swift,roambotics/swift,nathawes/swift,parkera/swift,rudkx/swift,xwu/swift,nathawes/swift,benlangmuir/swift,roambotics/swift,jmgc/swift,JGiola/swift,atrick/swift,glessard/swift,rudkx/swift,xwu/swift,parkera/swift,glessard/swift,hooman/swift,hooman/swift,xwu/swift,glessard/swift,gregomni/swift,atrick/swift,xwu/swift,nathawes/swift,roambotics/swift,hooman/swift,jmgc/swift,glessard/swift,jmgc/swift,ahoppen/swift,apple/swift,tkremenek/swift,CodaFi/swift,tkremenek/swift,nathawes/swift,parkera/swift,gregomni/swift,gregomni/swift,hooman/swift,benlangmuir/swift,roambotics/swift,parkera/swift,jmgc/swift,apple/swift,JGiola/swift,CodaFi/swift,nathawes/swift,parkera/swift,hooman/swift,JGiola/swift,ahoppen/swift,jmgc/swift,ahoppen/swift,ahoppen/swift,gregomni/swift,parkera/swift,hooman/swift,tkremenek/swift,atrick/swift,gregomni/swift,CodaFi/swift,gregomni/swift,tkremenek/swift,hooman/swift,rudkx/swift,roambotics/swift,apple/swift,glessard/swift,CodaFi/swift,ahoppen/swift,xwu/swift,roambotics/swift,nathawes/swift,benlangmuir/swift,jmgc/swift,rudkx/swift,rudkx/swift,tkremenek/swift,benlangmuir/swift,apple/swift,xwu/swift,parkera/swift,CodaFi/swift,apple/swift,atrick/swift