Avoid retaining all protobuf objects in DeserializedMemberScope

Object model for deserialized protobuf isn't very cheap, so
loading just our stdlib's packages several times (as we do in the IDE)
might lead to ~ 96 MB of retained memory just by these objects.

While in fact many of them remain unused

 #KT-21517 Fixed

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

@@ -73,7 +73,8 @@ fun createKotlinJavascriptPackageFragmentProvider(
             emptyList(),
             notFoundClasses,
             ContractDeserializerImpl(configuration),
-            platformDependentDeclarationFilter = PlatformDependentDeclarationFilter.NoPlatformDependent
+            platformDependentDeclarationFilter = PlatformDependentDeclarationFilter.NoPlatformDependent,
+            extensionRegistryLite = JsSerializerProtocol.extensionRegistry
     )
 
     for (packageFragment in packageFragments.filterIsInstance<KotlinJavascriptPackageFragment>()) {