Implement immutable prototype chains

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index e1df2b662ddc83e9d4c1a661dec9cbab8f9bf626..a466f5d6e3f6a9f0b3fe8ad97f5e1fedcaeefe67 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -4680,6 +4680,13 @@ bool Map::is_migration_target() {
   return IsMigrationTarget::decode(bit_field3());
 }
 
+void Map::set_immutable_proto(bool value) {
+  set_bit_field3(ImmutablePrototype::update(bit_field3(), value));
+}
+
+bool Map::is_immutable_proto() {
+  return ImmutablePrototype::decode(bit_field3());
+}
 
 void Map::set_new_target_is_base(bool value) {
   set_bit_field3(NewTargetIsBase::update(bit_field3(), value));
@@ -5586,8 +5593,25 @@ ACCESSORS(FunctionTemplateInfo, shared_function_info, Object,
 SMI_ACCESSORS(FunctionTemplateInfo, flag, kFlagOffset)
 
 ACCESSORS(ObjectTemplateInfo, constructor, Object, kConstructorOffset)
-ACCESSORS(ObjectTemplateInfo, internal_field_count, Object,
-          kInternalFieldCountOffset)
+ACCESSORS(ObjectTemplateInfo, data, Object, kDataOffset)
+int ObjectTemplateInfo::internal_field_count() const {
+  Object* value = data();
+  DCHECK(value->IsSmi());
+  return InternalFieldCount::decode(Smi::cast(value)->value());
+}
+void ObjectTemplateInfo::set_internal_field_count(int count) {
+  return set_data(Smi::FromInt(
+      InternalFieldCount::update(Smi::cast(data())->value(), count)));
+}
+bool ObjectTemplateInfo::immutable_proto() const {
+  Object* value = data();
+  DCHECK(value->IsSmi());
+  return IsImmutablePrototype::decode(Smi::cast(value)->value());
+}
+void ObjectTemplateInfo::set_immutable_proto(bool immutable) {
+  return set_data(Smi::FromInt(
+      IsImmutablePrototype::update(Smi::cast(data())->value(), immutable)));
+}
 
 ACCESSORS(AllocationSite, transition_info, Object, kTransitionInfoOffset)
 ACCESSORS(AllocationSite, nested_site, Object, kNestedSiteOffset)