message: Make node and registration getter const.
diff: @@ -208,7 +208,7 @@ class Interpreter {
  // TODO(aselle): Create a safe ArrayHandle interface to avoid exposing this
  // read/write access to structure
  const std::pair<TfLiteNode, TfLiteRegistration>* node_and_registration(
  - int node_index) {
  + int node_index) const {
  if (node_index >= nodes_and_registration_.size() || node_index < 0)
  return nullptr;
  return &nodes_and_registration_[node_index];
  