Wrap JSON and generator implementation in functions.

src/json-stringifier.h

Index: src/json-stringifier.h
diff --git a/src/json-stringifier.h b/src/json-stringifier.h
index fabc8f39299196e0d08b7f5f575b3c98a18db046..444de43e7bc79b04cc2aa0238f1159d62b774413 100644
--- a/src/json-stringifier.h
+++ b/src/json-stringifier.h
@@ -361,8 +361,9 @@ BasicJsonStringifier::Result BasicJsonStringifier::SerializeGeneric(
     bool deferred_comma,
     bool deferred_key) {
   Handle<JSObject> builtins(isolate_->native_context()->builtins(), isolate_);
-  Handle<JSFunction> builtin = Handle<JSFunction>::cast(Object::GetProperty(
-      isolate_, builtins, "JSONSerializeAdapter").ToHandleChecked());
+  Handle<JSFunction> builtin = Handle<JSFunction>::cast(
+      Object::GetProperty(isolate_, builtins, "$jsonSerializeAdapter")
+          .ToHandleChecked());
 
   Handle<Object> argv[] = { key, object };
   Handle<Object> result;