Migrate FastCloneShallowObjectStub to TurboFan

src/ast/ast.h

Index: src/ast/ast.h
diff --git a/src/ast/ast.h b/src/ast/ast.h
index 539a848370a22f39b11dd13467f34c8308183c65..581215600a7c2fa9b5d5f0ecce28e127cfd1251c 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -1453,7 +1453,8 @@ class ObjectLiteral final : public MaterializedLiteral {
   bool may_store_doubles() const { return may_store_doubles_; }
   bool has_elements() const { return has_elements_; }
   bool has_shallow_properties() const {
-    return depth() == 1 && !has_elements() && !may_store_doubles();
+    return depth() == 1 && !has_elements() &&
+           (FLAG_unbox_double_fields || !may_store_doubles());
   }
 
   // Decide if a property should be in the object boilerplate.