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

test/cctest/test-code-stub-assembler.cc

Index: test/cctest/test-code-stub-assembler.cc
diff --git a/test/cctest/test-code-stub-assembler.cc b/test/cctest/test-code-stub-assembler.cc
index d55c82e8eac28bcdb761c714f59db24f9823b5d1..4af399e4f6dc43dc929e38c3bfe97789233315f7 100644
--- a/test/cctest/test-code-stub-assembler.cc
+++ b/test/cctest/test-code-stub-assembler.cc
@@ -1626,7 +1626,7 @@ TEST(AllocateJSObjectFromMap) {
   FunctionTester ft(code, kNumParams);
 
   Handle<Map> maps[] = {
-      isolate->object_with_null_prototype_map(),
+      isolate->slow_object_with_null_prototype_map(),
       handle(isolate->object_function()->initial_map(), isolate),
       handle(isolate->array_function()->initial_map(), isolate),
   };
@@ -1661,11 +1661,42 @@ TEST(AllocateJSObjectFromMap) {
                 handle(object->elements()))
             .ToHandleChecked());
     VERIFY(result, object->map(), object->properties(), object->elements());
+    CHECK(!result->HasFastProperties());
 #ifdef VERIFY_HEAP
     isolate->heap()->Verify();
 #endif
   }
 }
+TEST(AllocateNameDictionary) {
+  Isolate* isolate(CcTest::InitIsolateOnce());
+  Factory* factory = isolate->factory();
+
+  const int kNumParams = 1;
+  CodeStubAssemblerTester m(isolate, kNumParams);
+
+  {
+    Node* capacity = m.Parameter(0);
+    Node* result = m.AllocateNameDictionary(m.SmiUntag(capacity));
+    m.Return(result);
+  }
+
+  Handle<Code> code = m.GenerateCode();
+  FunctionTester ft(code, kNumParams);
+
+  {
+    Handle<Object> empty_fixed_array = factory->empty_fixed_array();
+    for (int i = 2; i < 100; i *= 2) {
+      Handle<JSObject> result = Handle<JSObject>::cast(
+          ft.Call(handle(Smi::FromInt(i), isolate)).ToHandleChecked());
+      Handle<NameDictionary> dict = NameDictionary::New(
+          isolate, i, NOT_TENURED, USE_CUSTOM_MINIMUM_CAPACITY);
+      // Both dictionaries should be memory equal.
+      int size =
+          FixedArrayBase::kHeaderSize + (dict->length() - 1) * kPointerSize;
+      CHECK_EQ(0, memcmp(*dict, *result, size));
+    }
+  }
+}
 
 }  // namespace internal
 }  // namespace v8