We are going to deprecate `WITH_RUNTIME` directive. The main reason
behind this change is that `WITH_STDLIB` directive better describes
its meaning, specifically it will add kotlin stdlib to test's classpath.
Technically a backwards compatibility problem, as the new backend
*consistently* renamed `f$default` on `f` with `@JvmName("g")` to
`g` instead of `g$default`, so it all worked out. However, this
breaks when encountering libraries compiled with the non-IR backend.