Fix tests of splitted config feature

Summary:
The following PR fixes the tests used in the javascript port (it modifies gentest.rb).

These changes don't yet pass, it seems something is segfaulting somewhere. I have to check if it comes from nbind, the yoga library, or the node bridge itself. There's also some fails on the browser build, but it might be the same issue.
Closes https://github.com/facebook/yoga/pull/487

Reviewed By: emilsjolander

Differential Revision: D4778870

Pulled By: astreet

fbshipit-source-id: 936fbca564ec89738c78e50c4402c53eb6867dec

javascript/sources/Config.cc

@@ -0,0 +1,42 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <yoga/Yoga.h>
+
+#include "./Config.hh"
+
+/* static */ Config * Config::create(void)
+{
+    return new Config();
+}
+
+/* static */ void Config::destroy(Config * node)
+{
+    delete node;
+}
+
+Config::Config(void)
+: m_config(YGConfigNew())
+{
+}
+
+Config::~Config(void)
+{
+    YGConfigFree(m_config);
+}
+
+void Config::setExperimentalFeatureEnabled(int feature, bool enabled)
+{
+    YGConfigSetExperimentalFeatureEnabled(m_config, static_cast<YGExperimentalFeature>(feature), enabled);
+}
+
+bool Config::isExperimentalFeatureEnabled(int feature) const
+{
+    return YGConfigIsExperimentalFeatureEnabled(m_config, static_cast<YGExperimentalFeature>(feature));
+}