[Typechecker] Supress _modify synthesis if the wrapped property has observers
[Typechecker] Supress _modify synthesis if the wrapped property has observers

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