Add:创建 flutter go web 版

packages/flutter_web/test/widgets/semantics_event_test.dart

@@ -0,0 +1,56 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_web/semantics.dart';
+import 'package:flutter_web_test/flutter_web_test.dart';
+
+void main() {
+  test('SemanticsEvent.toString', () {
+    expect(
+      TestSemanticsEvent().toString(),
+      'TestSemanticsEvent()',
+    );
+    expect(
+      TestSemanticsEvent(number: 10).toString(),
+      'TestSemanticsEvent(number: 10)',
+    );
+    expect(
+      TestSemanticsEvent(text: 'hello').toString(),
+      'TestSemanticsEvent(text: hello)',
+    );
+    expect(
+      TestSemanticsEvent(text: 'hello', number: 10).toString(),
+      'TestSemanticsEvent(number: 10, text: hello)',
+    );
+  });
+  test('SemanticsEvent.toMap', () {
+    expect(
+        TestSemanticsEvent(text: 'hi', number: 11).toMap(), <String, dynamic>{
+      'type': 'TestEvent',
+      'data': <String, dynamic>{'text': 'hi', 'number': 11}
+    });
+    expect(
+        TestSemanticsEvent(text: 'hi', number: 11).toMap(nodeId: 123),
+        <String, dynamic>{
+          'type': 'TestEvent',
+          'nodeId': 123,
+          'data': <String, dynamic>{'text': 'hi', 'number': 11}
+        });
+  });
+}
+
+class TestSemanticsEvent extends SemanticsEvent {
+  TestSemanticsEvent({this.text, this.number}) : super('TestEvent');
+
+  final String text;
+  final int number;
+
+  @override
+  Map<String, dynamic> getDataMap() {
+    final Map<String, dynamic> result = <String, dynamic>{};
+    if (text != null) result['text'] = text;
+    if (number != null) result['number'] = number;
+    return result;
+  }
+}