[Web+Linux] Fix pressing Meta keys throws

lib/web_ui/lib/src/engine/raw_keyboard.dart

@@ -6,6 +6,7 @@ import 'dart:async';
 import 'dart:typed_data';
 
 import '../engine.dart'  show registerHotRestartListener;
+import 'browser_detection.dart';
 import 'dom.dart';
 import 'keyboard_binding.dart';
 import 'platform_dispatcher.dart';
@@ -133,6 +134,9 @@ class RawKeyboard {
         _lastMetaState |= modifierNumLock;
       } else if (event.key == 'ScrollLock') {
         _lastMetaState |= modifierScrollLock;
+      } else if (event.key == 'Meta' && operatingSystem == OperatingSystem.linux) {
+        // On Chrome Linux, metaState can be wrong when a Meta key is pressed.
+        _lastMetaState |= _modifierMeta;
       }
     }
     final Map<String, dynamic> eventData = <String, dynamic>{

lib/web_ui/test/engine/raw_keyboard_test.dart

@@ -7,6 +7,7 @@ import 'dart:typed_data';
 import 'package:quiver/testing/async.dart';
 import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
+import 'package:ui/src/engine/browser_detection.dart';
 import 'package:ui/src/engine/dom.dart';
 import 'package:ui/src/engine/raw_keyboard.dart';
 import 'package:ui/src/engine/services.dart';
@@ -151,6 +152,35 @@ void testMain() {
       RawKeyboard.instance!.dispose();
     });
 
+    // Regression test for https://github.com/flutter/flutter/issues/125672.
+    test('updates meta state for Meta key and wrong DOM event metaKey value', () {
+      RawKeyboard.initialize();
+
+      Map<String, dynamic>? dataReceived;
+      ui.window.onPlatformMessage = (String channel, ByteData? data,
+          ui.PlatformMessageResponseCallback? callback) {
+        dataReceived = const JSONMessageCodec().decodeMessage(data) as Map<String, dynamic>?;
+      };
+
+      // Purposely send an incoherent DOM event where Meta key is pressed but event.metaKey is not set to true.
+      final DomKeyboardEvent event = dispatchKeyboardEvent(
+        'keydown',
+        key: 'Meta',
+        code: 'MetaLeft',
+      );
+      expect(event.defaultPrevented, isFalse);
+      expect(dataReceived, <String, dynamic>{
+        'type': 'keydown',
+        'keymap': 'web',
+        'code': 'MetaLeft',
+        'key': 'Meta',
+        'location': 0,
+        'metaState': 0x8,
+        'keyCode': 0,
+      });
+      RawKeyboard.instance!.dispose();
+    }, skip: operatingSystem != OperatingSystem.linux);
+
     test('dispatches repeat events', () {
       RawKeyboard.initialize();