[FIR] Fix applying generated supertypes for classes without explicit supertypes

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirSupertypeGenerationExtension.kt

@@ -19,11 +19,11 @@ abstract class FirSupertypeGenerationExtension(session: FirSession) : FirPredica
     final override val name: FirExtensionPointName
         get() = NAME
 
-    override val extensionType: KClass<out FirExtension> = FirSupertypeGenerationExtension::class
+    final override val extensionType: KClass<out FirExtension> = FirSupertypeGenerationExtension::class
 
     abstract fun computeAdditionalSupertypes(
         classLikeDeclaration: FirClassLikeDeclaration,
-        resolvedSupertypes: List<FirTypeRef>
+        resolvedSupertypes: List<FirResolvedTypeRef>
     ): List<FirResolvedTypeRef>
 
     fun interface Factory : FirExtension.Factory<FirSupertypeGenerationExtension>

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirSupertypesResolution.kt

@@ -35,6 +35,7 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirTypeAliasSymbol
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.types.builder.buildErrorTypeRef
+import org.jetbrains.kotlin.fir.types.impl.FirImplicitBuiltinTypeRef
 import org.jetbrains.kotlin.fir.visitors.FirDefaultTransformer
 import org.jetbrains.kotlin.fir.visitors.FirDefaultVisitor
 import org.jetbrains.kotlin.fir.visitors.FirTransformer
@@ -120,7 +121,7 @@ open class FirApplySupertypesTransformer(
     }
 
     private fun applyResolvedSupertypesToClass(firClass: FirClass) {
-        if (firClass.superTypeRefs.any { it !is FirResolvedTypeRef }) {
+        if (firClass.superTypeRefs.any { it !is FirResolvedTypeRef || it is FirImplicitBuiltinTypeRef }) {
             val supertypeRefs = getResolvedSupertypeRefs(firClass)
 
             // TODO: Replace with an immutable version or transformer