[runtime] Object.create(null) creates a slow object

src/builtins/builtins-object.cc

Index: src/builtins/builtins-object.cc
diff --git a/src/builtins/builtins-object.cc b/src/builtins/builtins-object.cc
index 4536fc9b8a23e81bafafb8ad354d3ebac68b38f6..01f5ad45863df21f67a1fbae052206e74cc150db 100644
--- a/src/builtins/builtins-object.cc
+++ b/src/builtins/builtins-object.cc
@@ -494,6 +494,7 @@ void Builtins::Generate_ObjectCreate(CodeStubAssembler* a) {
   a->Bind(&no_properties);
   {
     Variable map(a, MachineRepresentation::kTagged);
+    Variable properties(a, MachineRepresentation::kTagged);
     Label non_null_proto(a), instantiate_map(a), good(a);
 
     a->Branch(a->WordEqual(prototype, a->NullConstant()), &good,
@@ -501,13 +502,16 @@ void Builtins::Generate_ObjectCreate(CodeStubAssembler* a) {
 
     a->Bind(&good);
     {
-      map.Bind(a->LoadContextElement(context,
-                                     Context::OBJECT_WITH_NULL_PROTOTYPE_MAP));
+      map.Bind(a->LoadContextElement(
+          context, Context::SLOW_OBJECT_WITH_NULL_PROTOTYPE_MAP));
+      properties.Bind(
+          a->AllocateNameDictionary(NameDictionary::kInitialCapacity));
       a->Goto(&instantiate_map);
     }
 
     a->Bind(&non_null_proto);
     {
+      properties.Bind(a->EmptyFixedArrayConstant());
       Node* object_function =
           a->LoadContextElement(context, Context::OBJECT_FUNCTION_INDEX);
       Node* object_function_map = a->LoadObjectField(
@@ -528,7 +532,8 @@ void Builtins::Generate_ObjectCreate(CodeStubAssembler* a) {
 
     a->Bind(&instantiate_map);
     {
-      Node* instance = a->AllocateJSObjectFromMap(map.value());
+      Node* instance =
+          a->AllocateJSObjectFromMap(map.value(), properties.value());
       a->Return(instance);
     }
   }