message: Support reloading tflite models into toco IR.
diff: @@ -113,15 +113,34 @@ void ImportOperators(
  << operators_table.size();
  }
  string opname = operators_table.at(index);
  +
  + // Find and use the appropriate operator deserialization factory.
  + std::unique_ptr<Operator> new_op = nullptr;
  if (ops_by_name.count(opname) == 0) {
  - LOG(FATAL) << "Op '" << opname << "' not supported";
  + string effective_opname = "TENSORFLOW_UNSUPPORTED";
  + if (ops_by_name.count(effective_opname) == 0) {
  + LOG(FATAL) << "Internal logic error: TENSORFLOW_UNSUPPORTED not found.";
  + }
  + new_op = ops_by_name.at(effective_opname)
  + ->Deserialize(input_op->builtin_options(),
  + input_op->custom_options());
  + if (TensorFlowUnsupportedOperator* unsupported_op =
  + dynamic_cast<TensorFlowUnsupportedOperator*>(new_op.get())) {
  + unsupported_op->tensorflow_op = opname;
  + // TODO(b/109932940): Remove this when quantized is removed.
  + // For now, we assume all ops are quantized.
  + unsupported_op->quantized = true;
  + } else {
  + LOG(FATAL) << "Expected a TensorFlowUnsupportedOperator";
  + }
  + } else {
  + new_op = ops_by_name.at(opname)->Deserialize(input_op->builtin_options(),
  + input_op->custom_options());
  }
  -
  - auto new_op = ops_by_name.at(opname)->Deserialize(
  - input_op->builtin_options(), input_op->custom_options());
  model->operators.emplace_back(new_op.release());
  auto* op = model->operators.back().get();
  + // Make sure all the inputs and outputs are hooked up.
  auto inputs = input_op->inputs();
  for (int i = 0; i < inputs->Length(); i++) {
  auto input_index = inputs->Get(i);
  