message: Add Quantize() to ref op registry.
diff: @@ -129,6 +129,7 @@ TfLiteRegistration* Register_LEAKY_RELU();
  TfLiteRegistration* Register_SQUARED_DIFFERENCE();
  TfLiteRegistration* Register_FILL();
  TfLiteRegistration* Register_MIRROR_PAD();
  +TfLiteRegistration* Register_QUANTIZE();
  namespace {
  @@ -278,6 +279,7 @@ BuiltinRefOpResolver::BuiltinRefOpResolver() {
  AddBuiltin(BuiltinOperator_SQUARED_DIFFERENCE, Register_SQUARED_DIFFERENCE());
  AddBuiltin(BuiltinOperator_FILL, Register_FILL());
  AddBuiltin(BuiltinOperator_MIRROR_PAD, Register_MIRROR_PAD());
  + AddBuiltin(BuiltinOperator_QUANTIZE, Register_QUANTIZE());
  // TODO(andrewharp, ahentz): Move these somewhere more appropriate so that
  // custom ops aren't always included by default.
  