Don't form a 'context-independent expr' reference to a member during

name annotation.

Instead, defer forming the member access expression or DeclRefExpr until
we build the use of ClassifyName's result. Just build an
UnresolvedLookupExpr to track the LookupResult until we're ready to
consume it.

This also reverts commit 2f7269b6 (other
than its testcase). That change was an attempted workaround for the same
problem.