Fix ChangeNotifier compilation error

Caused by: flutter/flutter#133060

Author: passsy

lib/src/utils/changenotifier2.dart

@@ -1,4 +1,4 @@
-import 'package:flutter/cupertino.dart';
+import 'package:flutter/foundation.dart';
 import 'package:wiredash/src/utils/object_util.dart';
 
 /// A [ChangeNotifier] but better
@@ -7,16 +7,34 @@ import 'package:wiredash/src/utils/object_util.dart';
 /// - Doesn't crash when [dispose] is called multiple times
 /// - Knows when disposed [isDisposed]
 class ChangeNotifier2 implements ChangeNotifier {
+  /// If true, the event [ObjectCreated] for this instance was dispatched to
+  /// [MemoryAllocations].
+  ///
+  /// As [ChangedNotifier] is used as mixin, it does not have constructor,
+  /// so we use [addListener] to dispatch the event.
+  bool _creationDispatched = false;
+
   bool _isDisposed = false;
+
   bool get isDisposed => _isDisposed;
 
   final List<void Function()> listeners = [];
 
+  ChangeNotifier2() {
+    if (kFlutterMemoryAllocationsEnabled) {
+      maybeDispatchObjectCreation();
+    }
+  }
+
   @override
   void addListener(void Function() listener) {
     if (isDisposed) {
       throw "$instanceName is already disposed.";
     }
+
+    if (kFlutterMemoryAllocationsEnabled) {
+      maybeDispatchObjectCreation();
+    }
     listeners.add(listener);
   }
 
@@ -36,6 +54,9 @@ class ChangeNotifier2 implements ChangeNotifier {
     }
     _isDisposed = true;
     listeners.clear();
+    if (kFlutterMemoryAllocationsEnabled && _creationDispatched) {
+      MemoryAllocations.instance.dispatchObjectDisposed(object: this);
+    }
   }
 
   @override
@@ -56,4 +77,18 @@ class ChangeNotifier2 implements ChangeNotifier {
     }
     notifyListeners();
   }
+
+  @override
+  void maybeDispatchObjectCreation() {
+    // Tree shaker does not include this method and the class MemoryAllocations
+    // if kFlutterMemoryAllocationsEnabled is false.
+    if (kFlutterMemoryAllocationsEnabled && !_creationDispatched) {
+      MemoryAllocations.instance.dispatchObjectCreated(
+        library: 'package:wiredash/src/utils/changenotifier2.dart',
+        className: '$ChangeNotifier2',
+        object: this,
+      );
+      _creationDispatched = true;
+    }
+  }
 }