message: [lite] Remove dead /useless code.
  1) These passes are done now during import.
  2) We are not passing a session now, so this code never runs.
  Keeping the Session argument as it will be used in a follow change.
diff: @@ -92,21 +92,6 @@ void AddTFToTFLConversionPasses(const toco::ModelFlags& model_flags,
  pass_manager->addPass(mlir::TF::CreateTFShapeInferencePass());
  }
  - if (session.hasValue()) {
  - // Add a pass that converts reference variables to resource variables.
  - pass_manager->addPass(
  - mlir::TF::
  - CreateConvertReadonlyReferenceVariablesToResourceVariablesPass());
  -
  - // Add a pass that promotes resource variable to the function arguments.
  - pass_manager->addPass(mlir::TF::CreatePromoteVarHandlesToArgsPass());
  -
  - // Add a pass that creates global tensors and converts the function
  - // arguments to the tf_saved_model.bound_input arguments.
  - pass_manager->addPass(
  - mlir::tf_saved_model::CreateLiftVariablesPass(session.getValue()));
  - }
  -
  // Keep this pass after the shape inference pass, which couldn't do shape
  // inference for non-tf ops.
  if (!pass_config.quant_specs.serialized_quant_stats.empty()) {
  