[web] Fix HtmlImage state pollution due to image.clone optimization (flutter/engine#17370)

* fix drawImage style when destination width==source
* Add regression test
* dartfmt
* update golden lock
* Addressed review comment
* remove transform reset since _drawImage is called

engine/src/flutter/lib/web_ui/lib/src/engine/bitmap_canvas.dart

@@ -364,6 +364,10 @@ class BitmapCanvas extends EngineCanvas {
     final ui.BlendMode blendMode = paint.blendMode;
     imgElement.style.mixBlendMode = _stringForBlendMode(blendMode);
     if (_canvasPool.isClipped) {
+      // Reset width/height since they may have been previously set.
+      imgElement.style
+        ..removeProperty('width')
+        ..removeProperty('height');
       final List<html.Element> clipElements = _clipContent(
           _canvasPool._clipStack, imgElement, p, _canvasPool.currentTransform);
       for (html.Element clipElement in clipElements) {
@@ -375,7 +379,10 @@ class BitmapCanvas extends EngineCanvas {
           transformWithOffset(_canvasPool.currentTransform, p).storage);
       imgElement.style
         ..transformOrigin = '0 0 0'
-        ..transform = cssTransform;
+        ..transform = cssTransform
+        // Reset width/height since they may have been previously set.
+        ..removeProperty('width')
+        ..removeProperty('height');
       rootElement.append(imgElement);
       _children.add(imgElement);
     }

engine/src/flutter/lib/web_ui/test/golden_tests/engine/canvas_draw_picture_test.dart

@@ -0,0 +1,122 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// @dart = 2.6
+import 'dart:html' as html;
+
+import 'package:ui/ui.dart';
+import 'package:ui/src/engine.dart';
+import 'package:test/test.dart';
+
+import 'package:web_engine_tester/golden_tester.dart';
+
+final Rect region = Rect.fromLTWH(0, 0, 500, 100);
+
+void main() async {
+  setUp(() async {
+    debugShowClipLayers = true;
+    SurfaceSceneBuilder.debugForgetFrameScene();
+    for (html.Node scene in html.document.querySelectorAll('flt-scene')) {
+      scene.remove();
+    }
+
+    await webOnlyInitializePlatform();
+    webOnlyFontCollection.debugRegisterTestFonts();
+    await webOnlyFontCollection.ensureFontsLoaded();
+  });
+
+  test('draw growing picture across frames', () async {
+    final SurfaceSceneBuilder builder = SurfaceSceneBuilder();
+    builder.pushClipRect(
+      const Rect.fromLTRB(0, 0, 100, 100),
+    );
+
+    _drawTestPicture(builder, 100, false);
+    builder.pop();
+
+    html.Element elm1 = builder.build().webOnlyRootElement;
+    html.document.body.append(elm1);
+
+    // Now draw picture again but at larger size.
+    final SurfaceSceneBuilder builder2 = SurfaceSceneBuilder();
+    builder2.pushClipRect(
+      const Rect.fromLTRB(0, 0, 100, 100),
+    );
+    // Now draw the picture at original target size, which will use a
+    // different code path that should normally not have width/height set
+    // on image element.
+    _drawTestPicture(builder2, 20, false);
+    builder2.pop();
+
+    elm1.remove();
+    html.document.body.append(builder2.build().webOnlyRootElement);
+
+    await matchGoldenFile('canvas_draw_picture_acrossframes.png',
+        region: region);
+  });
+
+  test('draw growing picture across frames clipped', () async {
+    final SurfaceSceneBuilder builder = SurfaceSceneBuilder();
+    builder.pushClipRect(
+      const Rect.fromLTRB(0, 0, 100, 100),
+    );
+
+    _drawTestPicture(builder, 100, true);
+    builder.pop();
+
+    html.Element elm1 = builder.build().webOnlyRootElement;
+    html.document.body.append(elm1);
+
+    // Now draw picture again but at larger size.
+    final SurfaceSceneBuilder builder2 = SurfaceSceneBuilder();
+    builder2.pushClipRect(
+      const Rect.fromLTRB(0, 0, 100, 100),
+    );
+    _drawTestPicture(builder2, 20, true);
+    builder2.pop();
+
+    elm1.remove();
+    html.document.body.append(builder2.build().webOnlyRootElement);
+
+    await matchGoldenFile('canvas_draw_picture_acrossframes_clipped.png',
+        region: region);
+  });
+}
+
+HtmlImage sharedImage;
+
+void _drawTestPicture(SceneBuilder builder, double targetSize, bool clipped) {
+  sharedImage ??= _createRealTestImage();
+  final EnginePictureRecorder recorder = PictureRecorder();
+  final RecordingCanvas canvas =
+      recorder.beginRecording(const Rect.fromLTRB(0, 0, 100, 100));
+  canvas.debugEnforceArbitraryPaint();
+  if (clipped) {
+    canvas.clipRRect(
+        RRect.fromLTRBR(0, 0, targetSize, targetSize, Radius.circular(4)));
+  }
+  canvas.drawImageRect(sharedImage, Rect.fromLTWH(0, 0, 20, 20),
+      Rect.fromLTWH(0, 0, targetSize, targetSize), Paint());
+  final Picture picture = recorder.endRecording();
+  builder.addPicture(
+    Offset.zero,
+    picture,
+  );
+}
+
+typedef PaintCallback = void Function(RecordingCanvas canvas);
+
+const String _base64Encoded20x20TestImage =
+    'iVBORw0KGgoAAAANSUhEUgAAABQAAAAUCAIAAAAC64paAAAACXBIWXMAAC4jAAAuIwF4pT92AAAA'
+    'B3RJTUUH5AMFFBksg4i3gQAAABl0RVh0Q29tbWVudABDcmVhdGVkIHdpdGggR0lNUFeBDhcAAAAj'
+    'SURBVDjLY2TAC/7jlWVioACMah4ZmhnxpyHG0QAb1UyZZgBjWAIm/clP0AAAAABJRU5ErkJggg==';
+
+HtmlImage _createRealTestImage() {
+  return HtmlImage(
+    html.ImageElement()
+      ..src = 'data:text/plain;base64,$_base64Encoded20x20TestImage',
+    20,
+    20,
+  );
+}