Polyline Decode incorrect results using Flutter Web

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class GeoPoint {
  GeoPoint(this.latitude, this.longitude);
  final double latitude;
  final double longitude;

  @override
  toString() {
    return '$latitude, $longitude';
  }
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Sandbox',
      theme: ThemeData(
        backgroundColor: Colors.white,
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: Container(child: Builder(builder: (context) {
        final geoString =
            r"dg_{Foovi`@WsBz@w@lj@hW`FvCfKMRx@@KAJSy@gKL}CqByfAgg@?uCRCOc@Nb@~[aDbHaE|FpChCsFiCrF}FqCcH`Eq`@rEiOsGiC|BsPkJkKl@tGJnAe@DJjA^nAzG\p@Z[x@jA`@bB|@u@Z|@fE}D~YnMZqA";

        final results = decodeEncodedPolyline(geoString);

        return Column(
          children: [
            //Text(geoString),
            Expanded(
                child: ListView.builder(
                    itemCount: results.length, itemBuilder: (context, index) => Text(results[index].toString(),style: TextStyle(fontSize: 14, color: Colors.black),))),
          ],
        );
      })),
    );
  }

  static List<GeoPoint> decodeEncodedPolyline(String encoded) {
    print('decode polyline: $encoded');
    List<GeoPoint> points = [];
    int index = 0, len = encoded.length;
    int lat = 0, lng = 0;

    while (index < len) {
      int b, shift = 0, result = 0;
      do {
        b = encoded.codeUnitAt(index++) - 63;
        result |= (b & 0x1f) << shift;
        shift += 5;
      } while (b >= 0x20);
      int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
      lat += dlat;

      shift = 0;
      result = 0;
      do {
        b = encoded.codeUnitAt(index++) - 63;
        result |= (b & 0x1f) << shift;
        shift += 5;
      } while (b >= 0x20);
      int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
      lng += dlng;
      GeoPoint p = new GeoPoint((lat / 1E5).toDouble(), (lng / 1E5).toDouble());
      points.add(p);
    }
    return points;
  }
}