Fix memory leak in ExpansionTile. (#147596)

Author: ksokolovskyi

packages/flutter/lib/src/material/expansion_tile.dart

@@ -613,6 +613,7 @@ class _ExpansionTileState extends State<ExpansionTile> with SingleTickerProvider
   void dispose() {
     _tileController._state = null;
     _animationController.dispose();
+    _heightFactor.dispose();
     _timer?.cancel();
     _timer = null;
     super.dispose();

packages/flutter/test/material/expansion_tile_test.dart

@@ -11,6 +11,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
 
 class TestIcon extends StatefulWidget {
   const TestIcon({super.key});
@@ -222,7 +223,10 @@ void main() {
     expect(iconColor(collapsedIconKey), foregroundColor);
   }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS,  TargetPlatform.macOS }));
 
-  testWidgets('ExpansionTile subtitle', (WidgetTester tester) async {
+  testWidgets('ExpansionTile subtitle',
+  // TODO(polina-c): remove when fixed https://github.com/flutter/flutter/issues/145600 [leak-tracking-opt-in]
+  experimentalLeakTesting: LeakTesting.settings.withTracked(classes: const <String>['CurvedAnimation']),
+  (WidgetTester tester) async {
     await tester.pumpWidget(
       const MaterialApp(
         home: Scaffold(