Fix stack overflow for mac build.

src/json-stringifier.h

Index: src/json-stringifier.h
diff --git a/src/json-stringifier.h b/src/json-stringifier.h
index 1aa72b71b4e08a3f519696488cb2efe2ed3fd0d4..74f38fe99cd3496f9ca69b44491d6a5ea3867c21 100644
--- a/src/json-stringifier.h
+++ b/src/json-stringifier.h
@@ -569,8 +569,7 @@ BasicJsonStringifier::Result BasicJsonStringifier::SerializeJSObject(
       !object->HasNamedInterceptor() &&
       object->elements()->length() == 0) {
     Handle<Map> map(object->map());
-    int num_desc = map->NumberOfOwnDescriptors();
-    for (int i = 0; i < num_desc; i++) {
+    for (int i = 0; i < map->NumberOfOwnDescriptors(); i++) {
       Handle<String> key(map->instance_descriptors()->GetKey(i), isolate_);
       PropertyDetails details = map->instance_descriptors()->GetDetails(i);
       if (details.IsDontEnum() || details.IsDeleted()) continue;