[CS] Tighten up check for unresolved member chain
[CS] Tighten up check for unresolved member chain

With the removal of TupleExpr and ParenExpr argument
lists, it's no longer sufficient to check whether
a given parent expr has a possible chain sub-expr,
as it might be a child that's unrelated to the chain
under consideration. For example, for a chain that's
an argument to a function call, we don't want to
walk up and consider the call expr to be an extension
of the chain just because it has a function expr.

Tighten up the check by comparing whether the given
sub-expr of a possible chain parent matches the
current expr in the chain.

JGiola/swift,benlangmuir/swift,gregomni/swift,rudkx/swift,JGiola/swift,atrick/swift,xwu/swift,atrick/swift,apple/swift,rudkx/swift,xwu/swift,gregomni/swift,benlangmuir/swift,rudkx/swift,rudkx/swift,benlangmuir/swift,JGiola/swift,glessard/swift,xwu/swift,ahoppen/swift,benlangmuir/swift,atrick/swift,glessard/swift,roambotics/swift,ahoppen/swift,xwu/swift,xwu/swift,apple/swift,apple/swift,roambotics/swift,gregomni/swift,ahoppen/swift,gregomni/swift,roambotics/swift,xwu/swift,gregomni/swift,apple/swift,JGiola/swift,benlangmuir/swift,glessard/swift,atrick/swift,atrick/swift,roambotics/swift,benlangmuir/swift,rudkx/swift,ahoppen/swift,JGiola/swift,apple/swift,ahoppen/swift,roambotics/swift,rudkx/swift,glessard/swift,apple/swift,atrick/swift,glessard/swift,glessard/swift,roambotics/swift,xwu/swift,ahoppen/swift,JGiola/swift,gregomni/swift