^KT-63860 Fixed
Review: https://jetbrains.team/p/kt/reviews/13334/timeline
The previous code was nonsense (I wrote it). It doesn't make sense to
subtract actualOverriddenDeclarations from expectOverriddenDeclarations.
Default parameters are mentioned on the expect side. So default params
in expect/actual supertypes won't be subtracted from
expectOverriddenDeclarations (but should be)