Fix AssertionError in CodegenUtil.getDelegates

Change getAllOverriddenDescriptors contracti, now it returns
original (not substituted) descriptors without any duplicates.

First of all it's necessary in CodegenUtil.getDelegates to avoid
duplicates (see assertion there), but also it's convenient for all
other usages of this method

 #KT-8154 Fixed

core/descriptors/src/org/jetbrains/kotlin/resolve/DescriptorUtils.java

@@ -469,6 +469,9 @@ public class DescriptorUtils {
         return classDescriptor.getModality() != Modality.FINAL || classDescriptor.getKind() == ClassKind.ENUM_CLASS;
     }
 
+    /**
+     * @return original (not substituted) descriptors without any duplicates
+     */
     @NotNull
     @SuppressWarnings("unchecked")
     public static <D extends CallableDescriptor> Set<D> getAllOverriddenDescriptors(@NotNull D f) {
@@ -481,7 +484,7 @@ public class DescriptorUtils {
         if (result.contains(current)) return;
         for (CallableDescriptor callableDescriptor : current.getOriginal().getOverriddenDescriptors()) {
             @SuppressWarnings("unchecked")
-            D descriptor = (D) callableDescriptor;
+            D descriptor = (D) callableDescriptor.getOriginal();
             collectAllOverriddenDescriptors(descriptor, result);
             result.add(descriptor);
         }

core/descriptors/src/org/jetbrains/kotlin/resolve/OverridingUtil.java

@@ -119,7 +119,7 @@ public class OverridingUtil {
 
         CallableDescriptor originalG = g.getOriginal();
         for (D overriddenFunction : DescriptorUtils.getAllOverriddenDescriptors(f)) {
-            if (DescriptorEquivalenceForOverrides.INSTANCE.areEquivalent(originalG, overriddenFunction.getOriginal())) return true;
+            if (DescriptorEquivalenceForOverrides.INSTANCE.areEquivalent(originalG, overriddenFunction)) return true;
         }
         return false;
     }