Fix stack overflow for mac build.

R=ulan@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/11358096

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12861 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

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;