[semantic-arc-opts] Refactor out reinitializing the worklist into method drainVisitedSinceLastMutationIntoWorklist and add some types/comments.
[semantic-arc-opts] Refactor out reinitializing the worklist into method drainVisitedSinceLastMutationIntoWorklist and add some types/comments.

I was doing this in two places. It makes sense to refactor it out as such.

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