Introduce COMMON_COROUTINES_TEST directive.
Every test with this directive is run twice: one time with
language version 1.2 and kotlin.coroutines.experimental package
and the other time with language version 1.3 and kotlin.coroutines
package. Each run is a separate method: with suffixes _1_2 and _1_3
respectively.
However, since codegen of release coroutines is not supported in JS
backend, we generate only one method: with suffix _1_2.
#KT-23362
Private suspend functions need to be generated as package-local, since
they are called from their continuations.
However, this means that they can be called from Java, which breaks
their private visibility.
Adding synthetic to them fixes the issue.
#KT-17584: Fixed
Sometimes instead of {POP, GETSTATIC Unit.INSTANCE, ARETURN} sequence
the codegen emits {CHECKCAST Unit, ARETURN} sequence, which breaks tail
call optimization. By replacing CHECKCAST with ARETURN we eliminate
this issue.
#KT-19790: Fixed
