HStoreNamedField for Smis optimized for x64

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 1717a5f4b59a8cba4db473b0e0634e9c9c437b93..47e8970603182cc9a48627791979188d4e9ab663 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -267,6 +267,9 @@ bool Object::HasValidElements() {
 
 MaybeObject* Object::AllocateNewStorageFor(Heap* heap,
                                            Representation representation) {
+  if (FLAG_track_fields && representation.IsSmi() && IsUninitialized()) {
+    return Smi::FromInt(0);
+  }
   if (!FLAG_track_double_fields) return this;
   if (!representation.IsDouble()) return this;
   if (IsUninitialized()) {