Do not load built-ins in old format, drop class_name extension

js/js.serializer/src/org/jetbrains/kotlin/serialization/js/KotlinJavascriptPackageFragment.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.serialization.ProtoBuf
 import org.jetbrains.kotlin.serialization.deserialization.DeserializedPackageFragment
 import org.jetbrains.kotlin.serialization.deserialization.NameResolverImpl
+import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedPackageMemberScope
 import org.jetbrains.kotlin.storage.StorageManager
 import java.io.InputStream
 
@@ -36,7 +37,15 @@ class KotlinJavascriptPackageFragment(
 
     override val classIdToProto: Map<ClassId, ProtoBuf.Class>? get() = null
 
-    override fun loadClassNames(packageProto: ProtoBuf.Package): Collection<Name> {
+    override fun computeMemberScope(): DeserializedPackageMemberScope {
+        val packageStream = loadResourceSure(serializedResourcePaths.getPackageFilePath(fqName))
+        val packageProto = ProtoBuf.Package.parseFrom(packageStream, serializedResourcePaths.extensionRegistry)
+        return DeserializedPackageMemberScope(
+                this, packageProto, nameResolver, packagePartSource = null, components = components, classNames = { loadClassNames() }
+        )
+    }
+
+    private fun loadClassNames(): Collection<Name> {
         val classesStream = loadResourceSure(KotlinJavascriptSerializedResourcePaths.getClassesInPackageFilePath(fqName))
         val classesProto = JsProtoBuf.Classes.parseFrom(classesStream, serializedResourcePaths.extensionRegistry)
         return classesProto.classNameList?.map { id -> nameResolver.getName(id) } ?: listOf()