run web tests only on browser

Author: Nurhan Turgut

packages/e2e/example/test_driver/example_e2e_web.dart

@@ -5,6 +5,8 @@
 // gestures. You can also use WidgetTester to find child widgets in the widget
 // tree, read text, and verify that the values of widget properties are correct.
 
+@TestOn('browser')
+
 import 'dart:html' as html;
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';