added support for web ; bumped dart_core_sdk version to 1.13.2

lib/utils.dart

@@ -1,22 +1,30 @@
 
 import 'dart:io' show Platform;
 
+import 'package:flutter/foundation.dart' show kIsWeb;
 import 'package:package_info_plus/package_info_plus.dart';
 
 String getRedirectURI() {
+  if (kIsWeb) {
+    // Use the current page's origin so the redirect URI always matches
+    // the host and port the app is actually served on.
+    final base = Uri.base;
+    final port = base.hasPort ? ':${base.port}' : '';
+    return '/${base.host}$port/auth.html';
+  }
   try {
     if (Platform.isAndroid) {
       return "";
     } else {
-      return "/localhost:3000/auth.html";
+      return "/localhost:8080/auth.html";
     }
   } catch (e) {
-    // Must be web
-    return "/localhost:3000/auth.html";
+    return "/localhost:8080/auth.html";
   }
 }
 
 Future<String> getCallbackUrlScheme() async {
+  if (kIsWeb) return "http";
   try {
     if (Platform.isAndroid) {
       PackageInfo packageInfo = await PackageInfo.fromPlatform();
@@ -25,7 +33,6 @@ Future<String> getCallbackUrlScheme() async {
       return "http";
     }
   } catch (e) {
-    // Must be web
     return "http";
   }
 }