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.
Without this directive the test can't be compiled by Kotlin/Native, because the box() function which is annotated with @ExperimentalContracts is called from the generated test runner source code that itself is not marked by this annotation.
vladislav.grechko