message: [tf.data] Remove outdated comment.
diff: @@ -92,8 +92,6 @@ class OptimizeDatasetOp : public UnaryDatasetOpKernel {
  TF_RETURN_IF_ERROR(ImportGraphDef({}, graph_def, &graph, nullptr));
  std::vector<Tensor> outputs;
  GraphRunner graph_runner(ctx->function_library()->device());
  - // Once rewrites that add/modify functions are introduced, we will need
  - // persist the results in a function library runtime.
  TF_RETURN_IF_ERROR(graph_runner.Run(&graph, ctx->function_library(), {},
  {output_node}, &outputs));
  TF_RETURN_IF_ERROR(GetDatasetFromVariantTensor(outputs[0], &input_));
  