CLJS-470: fix `resolve-var` (.contains s ".") case

The issue was that `defprotocol` in the core.clj macros file emits
the native type dispatch cases with `foo.-bar`, `resolve-var`
would treat this as normal var resolution which it is not - use of
the `.` in symbols without a namespace clearly represents some
kind of interop or implementation detail.

`resolve-var` no longers warns on symbols that include `.` but not
`/`.