These tests were added for suspend-conversions, it worked only
with new inference, but implementation was incorrect and had other
bugs, which were fixed in 1ac25259.
Support of suspend-conversions will be addressed later with a different
implementation (#KT-30703)
* The members of Result are isSuccess, isFailure, exceptionOrNull, getOrNull
* The rest of API is implemented via inline-only extensions
* There are two internal functions to hide detailed mechanics of an internal
Result.Failure class: createFailure and throwOnFailure
* Result.toString is explicit: either Success(v) or Failure(x)
See KT-26538
