download files in flutter web

gd_download_button.dart

import 'dart:html';

import 'package:flutter/material.dart';
import 'package:growdata_shared_web/service/api.dart';

class GdDownloadButton extends StatelessWidget {
  final String path; 
  final Api api;

  GdDownloadButton(this.path, this.api);

  void _startDownload() {
    AnchorElement ele = AnchorElement(href: api.basicAuthLinkFor(path));
    ele.click();
  }

  @override
  Widget build(BuildContext context) => RaisedButton.icon(
    label: Text("Download"),
    icon: Icon(Icons.file_download),
    onPressed: _startDownload
  );
}

path is in the form of collection/<id>
api.basicAuthLinkFor(path) builds something along the lines of:
$protocol://$domain:$port/$root/$majorVersion/$path/?access_token=$jwt