In the newly added test, prior to this change, JVM IR was generating
DefaultImpls classes with calls to things like
`kotlin/collections/MutableList$DefaultImpls.spliterator` and other
default methods present in JDK 8+. This obviously didn't make much
sense. Although these weren't explicitly mentioned anywhere in the
bytecode, they caused some validation tools to report errors (e.g.
animalsniffer used in arrow).
Alexander Udalov