message: Add shape check to TextLineDataset op
diff: @@ -383,10 +383,12 @@ REGISTER_OP("TextLineDataset")
  .Output("handle: variant")
  .SetIsStateful() // TODO(b/65524810): Source dataset ops must be marked
  // stateful to inhibit constant folding.
  - .SetShapeFn(shape_inference::ScalarShape); // TODO(mrry): validate
  - // that `filenames` is
  - // a scalar or a
  - // vector.
  + .SetShapeFn([](shape_inference::InferenceContext* c) {
  + shape_inference::ShapeHandle unused;
  + // `filenames` must be a scalar or a vector.
  + TF_RETURN_IF_ERROR(c->WithRankAtMost(c->input(0), 1, &unused));
  + return shape_inference::ScalarShape(c);
  + });
  REGISTER_OP("SqlDataset")
  .Input("driver_name: string")
  