message: Fix road polygon
diff: @@ -103,9 +103,12 @@ struct RoadCorridor {
  }
  bool ComputeRoadPolygon() {
  Polygon merged_polygon;
  + // merge all lane polygons
  for (const auto& lane_corr : unique_lane_corridors_) {
  - merged_polygon.ConcatenatePolygons(
  - lane_corr->GetMergedPolygon());
  + const auto& lanes = lane_corr->GetLanes();
  + for (const auto& lane : lanes) {
  + merged_polygon.ConcatenatePolygons(lane.second->GetPolygon());
  + }
  }
  road_polygon_ = merged_polygon;
  return true;
  