Always finish the timeline event logged by Element.inflateWidget (#101794)

dev/tracing_tests/test/inflate_widget_update_test.dart

+// Copyright 2014 The Flutter 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/scheduler.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'common.dart';
+
+void main() {
+  WidgetsFlutterBinding.ensureInitialized();
+  initTimelineTests();
+  test('Widgets with updated keys produce well formed timelines', () async {
+    await runFrame(() { runApp(const TestRoot()); });
+    await SchedulerBinding.instance.endOfFrame;
+
+    debugProfileBuildsEnabled = true;
+
+    await runFrame(() {
+      TestRoot.state.updateKey();
+    });
+
+    int buildCount = 0;
+    for (final TimelineEvent event in await fetchTimelineEvents()) {
+      if (event.json!['name'] == 'BUILD') {
+        final String ph = event.json!['ph'] as String;
+        if (ph == 'B') {
+          buildCount++;
+        } else if (ph == 'E') {
+          buildCount--;
+        }
+      }
+    }
+    expect(buildCount, 0);
+
+    debugProfileBuildsEnabled = false;
+  }, skip: isBrowser); // [intended] uses dart:isolate and io.
+}
+
+class TestRoot extends StatefulWidget {
+  const TestRoot({super.key});
+
+  static late TestRootState state;
+
+  @override
+  State<TestRoot> createState() => TestRootState();
+}
+
+class TestRootState extends State<TestRoot> {
+  final Key _globalKey = GlobalKey();
+  Key _localKey = UniqueKey();
+
+  @override
+  void initState() {
+    super.initState();
+    TestRoot.state = this;
+  }
+
+  void updateKey() {
+    setState(() {
+      _localKey = UniqueKey();
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      key: _localKey,
+      child: SizedBox(
+        key: _globalKey,
+        width: 100,
+        height: 100,
+      ),
+    );
+  }
+}

packages/flutter/lib/src/widgets/framework.dart

@@ -3792,6 +3792,7 @@ abstract class Element extends DiagnosticableTree implements BuildContext {
       );
     }
 
+    try {
       final Key? key = newWidget.key;
       if (key is GlobalKey) {
         final Element? newChild = _retakeInactiveElement(key, newWidget);
@@ -3815,10 +3816,11 @@ abstract class Element extends DiagnosticableTree implements BuildContext {
       newChild.mount(this, newSlot);
       assert(newChild._lifecycleState == _ElementLifecycle.active);
 
+      return newChild;
+    } finally {
       if (isTimelineTracked)
         Timeline.finishSync();
-
-    return newChild;
+    }
   }
 
   void _debugCheckForCycles(Element newChild) {