[web] Dispose a temporary image that may be created by instantiateImageCodecWithSize (#54096)

Fixes flutter/flutter#147066

Author: jason-simmons

lib/web_ui/lib/src/engine/canvaskit/image.dart

@@ -130,6 +130,7 @@ class CkResizingCodec extends ResizingCodec {
       return image;
     }
 
+    image.dispose();
     return CkImage(skImage, imageSource: ImageBitmapImageSource(bitmap));
   }
 }

lib/web_ui/test/canvaskit/image_test.dart

@@ -21,6 +21,11 @@ void main() {
 void testMain() {
   setUpCanvasKitTest();
 
+  tearDown(() {
+    ui.Image.onCreate = null;
+    ui.Image.onDispose = null;
+  });
+
   test('toImage succeeds', () async {
     final ui.Image image = await _createImage();
     expect(image.runtimeType.toString(), equals('CkImage'));
@@ -44,8 +49,6 @@ void testMain() {
 
     expect(onCreateInvokedCount, 2);
     expect(createdImage, image2);
-
-    ui.Image.onCreate = null;
   });
 
   test('dispose() invokes onDispose once', () async {
@@ -65,8 +68,6 @@ void testMain() {
 
     expect(onDisposeInvokedCount, 2);
     expect(disposedImage, image2);
-
-    ui.Image.onDispose = null;
   });
 
   test('fetchImage fetches image in chunks', () async {
@@ -106,6 +107,30 @@ void testMain() {
     expect(size?.width, 600);
     expect(size?.height, 300);
   });
+
+  test('instantiateImageCodecWithSize disposes temporary image', () async {
+    final Set<ui.Image> activeImages = <ui.Image>{};
+    ui.Image.onCreate = activeImages.add;
+    ui.Image.onDispose = activeImages.remove;
+
+    final ui.Image image = await _createImage();
+    final ByteData? imageData = await image.toByteData(format: ui.ImageByteFormat.png);
+    final ui.ImmutableBuffer imageBuffer = await ui.ImmutableBuffer.fromUint8List(imageData!.buffer.asUint8List());
+    image.dispose();
+
+    final ui.Codec codec = await ui.instantiateImageCodecWithSize(
+      imageBuffer,
+      getTargetSize: (w, h) => ui.TargetImageSize(width: w ~/ 2, height: h ~/ 2)
+    );
+    final ui.FrameInfo frameInfo = await codec.getNextFrame();
+
+    expect(activeImages.length, 1);
+
+    frameInfo.image.dispose();
+    codec.dispose();
+
+    expect(activeImages.length, 0);
+  });
 }
 
 Future<ui.Image> _createImage() => _createPicture().toImage(10, 10);