Don't run ExpectedActualDeclarationChecker on property accessors

One might think that it shouldn't be run because of 'if (declaration
!is KtNamedDeclaration) return' check in the 'check'-overload.

However, for default accessors we pass PSI for property, i.e.
KtProperty (see 'DeclarationCheckers.checkAccessors'), which
obviously passes this check

Note that we can't use `DescriptorToSourceUtils` here, because it's
returns `KtProperty` for default accessor too.

This commits adds specific check for that case, to avoid exception in
KT-28385. Ideal solution would be to either don't launch checkers on
such parameters, or explicitly declare semantic of the
'declaration'-parameter, e.g. to rename it to 'reportOn' (see KT-28403
for discussion)

^KT-28385 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt

@@ -49,6 +49,9 @@ class ExpectedActualDeclarationChecker(val argumentExtractors: List<ActualAnnota
     override fun check(declaration: KtDeclaration, descriptor: DeclarationDescriptor, context: DeclarationCheckerContext) {
         if (!context.languageVersionSettings.supportsFeature(LanguageFeature.MultiPlatformProjects)) return
 
+        // Note that this check is necessary, because for default accessors KtProperty is passed for KtDeclaration, so this
+        // case won't be covered by the next check (also, it accidentally fixes KT-28385)
+        if (descriptor is PropertyAccessorDescriptor) return
         if (declaration !is KtNamedDeclaration) return
         if (descriptor !is MemberDescriptor || DescriptorUtils.isEnumEntry(descriptor)) return