Fix check for local classes in approximating string table

Take local/anonymous classes and their inner classes into account.
Simplify approximation: use first available super classifier instead
of first super class. This approximation should only happen for
private declarations that were not previously approximated by frontend.
So basically the only requirement for the approximated types is to be
denotable. Note that this only works if the types are not used later.
JVM uses a different string table implementatin as it needs exact
types of private members for reflection.

^KT-20996 Fixed

compiler/serialization/src/org/jetbrains/kotlin/serialization/ApproximatingStringTable.kt

@@ -13,19 +13,11 @@ import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.descriptorUtil.classId
 import org.jetbrains.kotlin.resolve.descriptorUtil.getAllSuperClassifiers
 
-open class ApproximatingStringTable : StringTableImpl() {
+class ApproximatingStringTable : StringTableImpl() {
     override fun getLocalClassIdReplacement(descriptor: ClassifierDescriptorWithTypeParameters): ClassId? {
-        return if (descriptor.containingDeclaration is CallableMemberDescriptor) {
-            val superClassifiers = descriptor.getAllSuperClassifiers()
-                .mapNotNull { it as ClassifierDescriptorWithTypeParameters }
-                .filter { it != descriptor }
-                .toList()
-            if (superClassifiers.size == 1) {
-                superClassifiers[0].classId
-            } else {
-                val superClass = superClassifiers.find { !DescriptorUtils.isInterface(it) }
-                superClass?.classId ?: ClassId.topLevel(StandardNames.FqNames.any.toSafe())
-            }
+        return if (DescriptorUtils.isLocal(descriptor)) {
+            descriptor.getAllSuperClassifiers().firstOrNull()?.classId
+                ?: ClassId.topLevel(StandardNames.FqNames.any.toSafe())
         } else {
             super.getLocalClassIdReplacement(descriptor)
         }