Minor, drop strange method from SerializerExtension

core/serialization/src/org/jetbrains/jet/descriptors/serialization/DescriptorSerializer.java

@@ -24,7 +24,10 @@ import org.jetbrains.jet.lang.resolve.MemberComparator;
 import org.jetbrains.jet.lang.types.*;
 import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
 
 import static org.jetbrains.jet.lang.resolve.DescriptorUtils.*;
 
@@ -34,10 +37,6 @@ public class DescriptorSerializer {
     private final Interner<TypeParameterDescriptor> typeParameters;
     private final SerializerExtension extension;
 
-    public DescriptorSerializer() {
-        this(SerializerExtension.DEFAULT);
-    }
-
     public DescriptorSerializer(@NotNull SerializerExtension extension) {
         this(new NameTable(), new Interner<TypeParameterDescriptor>(), extension);
     }
@@ -75,7 +74,7 @@ public class DescriptorSerializer {
             builder.addTypeParameter(local.typeParameter(typeParameterDescriptor));
         }
 
-        if (extension.hasSupertypes(classDescriptor)) {
+        if (!KotlinBuiltIns.getInstance().isSpecialClassWithNoSupertypes(classDescriptor)) {
             // Special classes (Any, Nothing) have no supertypes
             for (JetType supertype : classDescriptor.getTypeConstructor().getSupertypes()) {
                 builder.addSupertype(local.type(supertype));

core/serialization/src/org/jetbrains/jet/descriptors/serialization/SerializerExtension.java

@@ -18,16 +18,11 @@ package org.jetbrains.jet.descriptors.serialization;
 
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.descriptors.CallableMemberDescriptor;
-import org.jetbrains.jet.lang.descriptors.ClassDescriptor;
 import org.jetbrains.jet.lang.descriptors.ValueParameterDescriptor;
 
 public abstract class SerializerExtension {
     public static final SerializerExtension DEFAULT = new SerializerExtension() {};
 
-    public boolean hasSupertypes(@NotNull ClassDescriptor descriptor) {
-        return true;
-    }
-
     public void serializeCallable(
             @NotNull CallableMemberDescriptor callable,
             @NotNull ProtoBuf.Callable.Builder proto,