ASTScope: Fix SubscriptDeclScope source range
ASTScope: Fix SubscriptDeclScope source range

The source range needs to contain any attributes on the subscript
declaration, since those might create child scopes (@_specialize,
property wrappers, etc).

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