message: [XLA] Make not having is_dynamic_dimensions a warning rather than an error
  Since we currently don't require this field, and accept protos that don't have it, it's probably better not to spam the ERROR logs if the field is empty.
diff: @@ -34,8 +34,12 @@ Shape::Shape(const ShapeProto& shape_proto) {
  // instead of a constructor.
  if (shape_proto.dimensions_size() !=
  shape_proto.is_dynamic_dimension_size()) {
  + if (shape_proto.is_dynamic_dimension_size() != 0) {
  LOG(ERROR) << "Malformed shape proto: number of is_dynamic_dimension "
  "fields does not match number of dimension fields";
  + } else {
  + LOG(WARNING) << "Malformed shape proto: is_dynamic_dimension is empty";
  + }
  }
  int64 num_dynamic_dimension_fields = std::min(
  shape_proto.dimensions_size(), shape_proto.is_dynamic_dimension_size());
  