Fix KeyboardManager's synthesization (#88967)

This PR fixes KeyboardManager's key event synthesization logic, which were dispatching events with incorrect keys, making subsequent key events crash the app.

packages/flutter/lib/src/services/hardware_keyboard.dart

@@ -881,7 +881,7 @@ class KeyEventManager {
     for (final PhysicalKeyboardKey key in physicalKeysPressed.difference(_rawKeyboard.physicalKeysPressed)) {
       _keyEventsSinceLastMessage.add(KeyUpEvent(
         physicalKey: key,
-        logicalKey: _hardwareKeyboard.lookUpLayout(physicalKey)!,
+        logicalKey: _hardwareKeyboard.lookUpLayout(key)!,
         timeStamp: timeStamp,
         synthesized: true,
       ));
@@ -889,7 +889,7 @@ class KeyEventManager {
     for (final PhysicalKeyboardKey key in _rawKeyboard.physicalKeysPressed.difference(physicalKeysPressed)) {
       _keyEventsSinceLastMessage.add(KeyDownEvent(
         physicalKey: key,
-        logicalKey: _rawKeyboard.lookUpLayout(physicalKey)!,
+        logicalKey: _rawKeyboard.lookUpLayout(key)!,
         timeStamp: timeStamp,
         synthesized: true,
       ));

packages/flutter/test/services/hardware_keyboard_test.dart

@@ -4,6 +4,7 @@
 
 import 'dart:ui' as ui;
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -67,6 +68,34 @@ void main() {
       equals(<KeyboardLockMode>{}));
   }, variant: KeySimulatorTransitModeVariant.keyDataThenRawKeyData());
 
+  testWidgets('KeyboardManager synthesizes modifier keys in rawKeyData mode', (WidgetTester tester) async {
+    final List<KeyEvent> events = <KeyEvent>[];
+    HardwareKeyboard.instance.addHandler((KeyEvent event) {
+      events.add(event);
+      return false;
+    });
+    // While ShiftLeft is held (the event of which was skipped), press keyA.
+    final Map<String, dynamic> rawMessage = kIsWeb ? (
+      KeyEventSimulator.getKeyData(
+        LogicalKeyboardKey.keyA,
+        platform: 'web',
+      )..['metaState'] = RawKeyEventDataWeb.modifierShift
+    ) : (
+      KeyEventSimulator.getKeyData(
+        LogicalKeyboardKey.keyA,
+        platform: 'android',
+      )..['metaState'] = RawKeyEventDataAndroid.modifierLeftShift | RawKeyEventDataAndroid.modifierShift
+    );
+    tester.binding.keyEventManager.handleRawKeyMessage(rawMessage);
+    expect(events, hasLength(2));
+    expect(events[0].physicalKey, PhysicalKeyboardKey.shiftLeft);
+    expect(events[0].logicalKey, LogicalKeyboardKey.shiftLeft);
+    expect(events[0].synthesized, true);
+    expect(events[1].physicalKey, PhysicalKeyboardKey.keyA);
+    expect(events[1].logicalKey, LogicalKeyboardKey.keyA);
+    expect(events[1].synthesized, false);
+  });
+
   testWidgets('Dispatch events to all handlers', (WidgetTester tester) async {
     final FocusNode focusNode = FocusNode();
     final List<int> logs = <int>[];