[Effects handling] Eliminate Context::Kind::RethrowingFunction.
[Effects handling] Eliminate Context::Kind::RethrowingFunction.

We can determine whether we have a rethrowing function based on the
function declaration itself.

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