Revert "Redo make inspector weakly referencing the inspected objects." (#128506)

Reverts flutter/flutter#128471

It looks like one of the tests modified by this PR is still failing: https://ci.chromium.org/ui/p/flutter/builders/prod/Mac%20framework_tests_widgets/11385/overview

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

@@ -680,39 +680,11 @@ typedef InspectorSelectionChangedCallback = void Function();
 
 /// Structure to help reference count Dart objects referenced by a GUI tool
 /// using [WidgetInspectorService].
-///
-/// Does not hold the object from garbage collection.
-@visibleForTesting
-class InspectorReferenceData {
-  /// Creates an instance of [InspectorReferenceData].
-  InspectorReferenceData(Object object, this.id) {
-    // These types are not supported by [WeakReference].
-    // See https://api.dart.dev/stable/3.0.2/dart-core/WeakReference-class.html
-    if (object is String || object is num || object is bool) {
-      _value = object;
-      return;
-    }
-
-    _ref = WeakReference<Object>(object);
-  }
-
-  WeakReference<Object>? _ref;
-
-  Object? _value;
-
-  /// The id of the object in the widget inspector records.
-  final String id;
+class _InspectorReferenceData {
+  _InspectorReferenceData(this.object);
 
-  /// The number of times the object has been referenced.
+  final Object object;
   int count = 1;
-
-  /// The value.
-  Object? get value {
-    if (_ref != null) {
-      return _ref!.target;
-    }
-    return _value;
-  }
 }
 
 // Production implementation of [WidgetInspectorService].
@@ -770,9 +742,9 @@ mixin WidgetInspectorService {
   /// The VM service protocol does not keep alive object references so this
   /// class needs to manually manage groups of objects that should be kept
   /// alive.
-  final Map<String, Set<InspectorReferenceData>> _groups = <String, Set<InspectorReferenceData>>{};
-  final Map<String, InspectorReferenceData> _idToReferenceData = <String, InspectorReferenceData>{};
-  final WeakMap<Object, String> _objectToId = WeakMap<Object, String>();
+  final Map<String, Set<_InspectorReferenceData>> _groups = <String, Set<_InspectorReferenceData>>{};
+  final Map<String, _InspectorReferenceData> _idToReferenceData = <String, _InspectorReferenceData>{};
+  final Map<Object, String> _objectToId = Map<Object, String>.identity();
   int _nextId = 0;
 
   /// The pubRootDirectories that are currently configured for the widget inspector.
@@ -1298,22 +1270,20 @@ mixin WidgetInspectorService {
   /// references from a different group.
   @protected
   void disposeGroup(String name) {
-    final Set<InspectorReferenceData>? references = _groups.remove(name);
+    final Set<_InspectorReferenceData>? references = _groups.remove(name);
     if (references == null) {
       return;
     }
     references.forEach(_decrementReferenceCount);
   }
 
-  void _decrementReferenceCount(InspectorReferenceData reference) {
+  void _decrementReferenceCount(_InspectorReferenceData reference) {
     reference.count -= 1;
     assert(reference.count >= 0);
     if (reference.count == 0) {
-      final Object? value = reference.value;
-      if (value != null) {
-          _objectToId.remove(value);
-      }
-      _idToReferenceData.remove(reference.id);
+      final String? id = _objectToId.remove(reference.object);
+      assert(id != null);
+      _idToReferenceData.remove(id);
     }
   }
 
@@ -1325,15 +1295,14 @@ mixin WidgetInspectorService {
       return null;
     }
 
-    final Set<InspectorReferenceData> group = _groups.putIfAbsent(groupName, () => Set<InspectorReferenceData>.identity());
+    final Set<_InspectorReferenceData> group = _groups.putIfAbsent(groupName, () => Set<_InspectorReferenceData>.identity());
     String? id = _objectToId[object];
-    InspectorReferenceData referenceData;
+    _InspectorReferenceData referenceData;
     if (id == null) {
-      // TODO(polina-c): comment here why we increase memory footprint by the prefix 'inspector-'.
       id = 'inspector-$_nextId';
       _nextId += 1;
       _objectToId[object] = id;
-      referenceData = InspectorReferenceData(object, id);
+      referenceData = _InspectorReferenceData(object);
       _idToReferenceData[id] = referenceData;
       group.add(referenceData);
     } else {
@@ -1363,11 +1332,11 @@ mixin WidgetInspectorService {
       return null;
     }
 
-    final InspectorReferenceData? data = _idToReferenceData[id];
+    final _InspectorReferenceData? data = _idToReferenceData[id];
     if (data == null) {
       throw FlutterError.fromParts(<DiagnosticsNode>[ErrorSummary('Id does not exist.')]);
     }
-    return data.value;
+    return data.object;
   }
 
   /// Returns the object to introspect to determine the source location of an
@@ -1399,7 +1368,7 @@ mixin WidgetInspectorService {
       return;
     }
 
-    final InspectorReferenceData? referenceData = _idToReferenceData[id];
+    final _InspectorReferenceData? referenceData = _idToReferenceData[id];
     if (referenceData == null) {
       throw FlutterError.fromParts(<DiagnosticsNode>[ErrorSummary('Id does not exist')]);
     }
@@ -3744,54 +3713,3 @@ class _WidgetFactory {
 // recognize the annotation.
 // ignore: library_private_types_in_public_api
 const _WidgetFactory widgetFactory = _WidgetFactory();
-
-/// Does not hold keys from garbage collection.
-@visibleForTesting
-class WeakMap<K, V> {
-  Expando<Object> _objects = Expando<Object>();
-
-  /// Strings, numbers, booleans.
-  final Map<K, V> _primitives = <K, V>{};
-
-  bool _isPrimitive(Object? key) {
-    return key == null || key is String || key is num || key is bool;
-  }
-
-  /// Returns the value for the given [key] or null if [key] is not in the map
-  /// or garbage collected.
-  ///
-  /// Does not support records to act as keys.
-  V? operator [](K key){
-    if (_isPrimitive(key)) {
-      return _primitives[key];
-    } else {
-      return _objects[key!] as V?;
-    }
-  }
-
-  /// Associates the [key] with the given [value].
-  void operator []=(K key, V value){
-    if (_isPrimitive(key)) {
-      _primitives[key] = value;
-    } else {
-      _objects[key!] = value;
-    }
-  }
-
-  /// Removes the value for the given [key] from the map.
-  V? remove(K key) {
-    if (_isPrimitive(key)) {
-      return _primitives.remove(key);
-    } else {
-      final V? result = _objects[key!]  as V?;
-      _objects[key] = null;
-      return result;
-    }
-  }
-
-  /// Removes all pairs from the map.
-  void clear() {
-    _objects = Expando<Object>();
-    _primitives.clear();
-  }
-}