GoldenFileComparators should dispose created Image objects. (#136716)

packages/flutter/test/animation/live_binding_test.dart

@@ -137,7 +137,5 @@ void main() {
     );
   },
     skip: isBrowser, // [intended] https://github.com/flutter/flutter/issues/56001
-    // TODO(polina-c): remove after fixing https://github.com/flutter/flutter/issues/136513
-    leakTrackingTestConfig: const LeakTrackingTestConfig(notDisposedAllowList: <String, int?>{'Image': 4}),
   );
 }

packages/flutter_goldens/lib/flutter_goldens.dart

@@ -534,10 +534,12 @@ class FlutterLocalFileComparator extends FlutterGoldenFileComparator with LocalC
     );
 
     if (result.passed) {
+      result.dispose();
       return true;
     }
 
     final String error = await generateFailureOutput(result, golden, basedir);
+    result.dispose();
     throw FlutterError(error);
   }
 }

packages/flutter_test/lib/src/_goldens_io.dart

@@ -96,12 +96,15 @@ class LocalFileComparator extends GoldenFileComparator with LocalComparisonOutpu
       await getGoldenBytes(golden),
     );
 
-    if (!result.passed) {
+    if (result.passed) {
+      result.dispose();
+      return true;
+    }
+
     final String error = await generateFailureOutput(result, golden, basedir);
+    result.dispose();
     throw FlutterError(error);
   }
-    return result.passed;
-  }
 
   @override
   Future<void> update(Uri golden, Uint8List imageBytes) async {

packages/flutter_test/lib/src/goldens.dart

@@ -5,6 +5,7 @@
 import 'dart:typed_data';
 import 'dart:ui';
 
+import 'package:meta/meta.dart';
 import 'package:path/path.dart' as path;
 
 import '_goldens_io.dart' if (dart.library.html) '_goldens_web.dart' as goldens;
@@ -342,4 +343,16 @@ class ComparisonResult {
 
   /// The calculated percentage of pixel difference between two images.
   final double diffPercent;
+
+  /// Disposes the images held by this [ComparisonResult].
+  @mustCallSuper
+  void dispose() {
+    if (diffs == null) {
+      return;
+    }
+
+    for (final MapEntry<String, Image> entry in diffs!.entries) {
+      entry.value.dispose();
+    }
+  }
 }

packages/flutter_test/test/goldens_test.dart

@@ -5,6 +5,7 @@
 import 'dart:async';
 import 'dart:io' as io;
 import 'dart:typed_data';
+import 'dart:ui' as ui;
 
 import 'package:file/memory.dart';
 import 'package:flutter/foundation.dart' show DiagnosticLevel, DiagnosticPropertiesBuilder, DiagnosticsNode, FlutterError;
@@ -322,4 +323,34 @@ void main() {
       });
     });
   });
+
+  group('ComparisonResult', () {
+    group('dispose', () {
+      test('disposes diffs images', () async {
+        final ui.Image image1 = await createTestImage(width: 10, height: 10, cache: false);
+        final ui.Image image2 = await createTestImage(width: 15, height: 5, cache: false);
+        final ui.Image image3 = await createTestImage(width: 5, height: 10, cache: false);
+
+        final ComparisonResult result = ComparisonResult(
+          passed: false,
+          diffPercent: 1.0,
+          diffs: <String, ui.Image>{
+            'image1': image1,
+            'image2': image2,
+            'image3': image3,
+          }
+        );
+
+        expect(image1.debugDisposed, isFalse);
+        expect(image2.debugDisposed, isFalse);
+        expect(image3.debugDisposed, isFalse);
+
+        result.dispose();
+
+        expect(image1.debugDisposed, isTrue);
+        expect(image2.debugDisposed, isTrue);
+        expect(image3.debugDisposed, isTrue);
+      });
+    });
+  });
 }