[web] more null-safe tests (#26712)

lib/web_ui/test/canvaskit/vertices_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
 import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
 import 'package:ui/src/engine.dart';
@@ -29,7 +28,7 @@ void testMain() {
       canvas.drawVertices(
         vertices,
         ui.BlendMode.srcOver,
-        ui.Paint(),
+        CkPaint(),
       );
       vertices.delete();
     });
@@ -37,7 +36,7 @@ void testMain() {
   }, skip: isIosSafari);
 }
 
-ui.Vertices _testVertices() {
+CkVertices _testVertices() {
   return ui.Vertices(
     ui.VertexMode.triangles,
     <ui.Offset>[
@@ -56,5 +55,5 @@ ui.Vertices _testVertices() {
       ui.Color.fromRGBO(0, 0, 255, 1.0),
     ],
     indices: <int>[0, 1, 2],
-  );
+  ) as CkVertices;
 }

lib/web_ui/test/engine/image/html_image_codec_test.dart

@@ -2,7 +2,6 @@
 // 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:async';
 import 'dart:typed_data';
 
@@ -103,7 +102,7 @@ void testMain() async {
   group('ImageCodecUrl', () {
     test('loads sample image from web', () async {
       final Uri uri = Uri.base.resolve('sample_image1.png');
-      final HtmlCodec codec = await ui.webOnlyInstantiateImageCodecFromUrl(uri);
+      final HtmlCodec codec = await ui.webOnlyInstantiateImageCodecFromUrl(uri) as HtmlCodec;
       final ui.FrameInfo frameInfo = await codec.getNextFrame();
       expect(frameInfo.image, isNotNull);
       expect(frameInfo.image.width, 100);
@@ -114,7 +113,7 @@ void testMain() async {
       final HtmlCodec codec = await ui.webOnlyInstantiateImageCodecFromUrl(uri,
           chunkCallback: (int loaded, int total) {
         buffer.write('$loaded/$total,');
-      });
+      }) as HtmlCodec;
       await codec.getNextFrame();
       expect(buffer.toString(), '0/100,100/100,');
     });

lib/web_ui/test/engine/semantics/accessibility_test.dart

@@ -2,7 +2,6 @@
 // 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:async' show Future;
 import 'dart:html';
 
@@ -10,7 +9,7 @@ import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
 import 'package:ui/src/engine.dart';
 
-const MessageCodec<dynamic> codec = StandardMessageCodec();
+const StandardMessageCodec codec = StandardMessageCodec();
 const String testMessage = 'This is an tooltip.';
 const Map<dynamic, dynamic> testInput = <dynamic, dynamic>{
   'data': <dynamic, dynamic>{'message': testMessage}
@@ -21,7 +20,7 @@ void main() {
 }
 
 void testMain() {
-  AccessibilityAnnouncements accessibilityAnnouncements;
+  late AccessibilityAnnouncements accessibilityAnnouncements;
 
   group('$AccessibilityAnnouncements', () {
     setUp(() {
@@ -45,7 +44,7 @@ void testMain() {
         isNotNull,
       );
       final LabelElement input =
-          document.getElementById('accessibility-element');
+          document.getElementById('accessibility-element') as LabelElement;
       expect(input.getAttribute('aria-live'), equals('polite'));
       expect(input.text, testMessage);
 

lib/web_ui/test/engine/semantics/semantics_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.9
 @TestOn('chrome || safari || firefox')
 
 import 'dart:async';
@@ -88,7 +87,7 @@ void _testEngineSemanticsOwner() {
 
     // Synthesize a click on the placeholder.
     final html.Element placeholder =
-        appShadowRoot.querySelector('flt-semantics-placeholder');
+        appShadowRoot.querySelector('flt-semantics-placeholder')!;
 
     expect(placeholder.isConnected, isTrue);
 
@@ -101,7 +100,7 @@ void _testEngineSemanticsOwner() {
 
     // On mobile semantics is enabled asynchronously.
     if (isMobile) {
-      while (placeholder.isConnected) {
+      while (placeholder.isConnected!) {
         await Future<void>.delayed(const Duration(milliseconds: 50));
       }
     }
@@ -114,7 +113,7 @@ void _testEngineSemanticsOwner() {
     expect(semantics().semanticsEnabled, isFalse);
 
     final html.Element placeholder =
-        appShadowRoot.querySelector('flt-semantics-placeholder');
+        appShadowRoot.querySelector('flt-semantics-placeholder')!;
 
     expect(placeholder.isConnected, isTrue);
 
@@ -159,12 +158,12 @@ void _testEngineSemanticsOwner() {
     // Create
     renderLabel('Hello');
 
-    final Map<int, SemanticsObject> tree = semantics().debugSemanticsTree;
+    final Map<int, SemanticsObject> tree = semantics().debugSemanticsTree!;
     expect(tree.length, 2);
-    expect(tree[0].id, 0);
-    expect(tree[0].element.tagName.toLowerCase(), 'flt-semantics');
-    expect(tree[1].id, 1);
-    expect(tree[1].label, 'Hello');
+    expect(tree[0]!.id, 0);
+    expect(tree[0]!.element.tagName.toLowerCase(), 'flt-semantics');
+    expect(tree[1]!.id, 1);
+    expect(tree[1]!.label, 'Hello');
 
     expectSemanticsTree('''
 <sem style="$rootSemanticStyle">
@@ -383,9 +382,9 @@ void _testContainer() {
 </sem>''');
 
     final html.Element parentElement =
-        appShadowRoot.querySelector('flt-semantics');
+        appShadowRoot.querySelector('flt-semantics')!;
     final html.Element container =
-        appShadowRoot.querySelector('flt-semantics-container');
+        appShadowRoot.querySelector('flt-semantics-container')!;
 
     if (isMacOrIOS) {
       expect(parentElement.style.top, '0px');
@@ -431,9 +430,9 @@ void _testContainer() {
 </sem>''');
 
     final html.Element parentElement =
-        appShadowRoot.querySelector('flt-semantics');
+        appShadowRoot.querySelector('flt-semantics')!;
     final html.Element container =
-        appShadowRoot.querySelector('flt-semantics-container');
+        appShadowRoot.querySelector('flt-semantics-container')!;
 
     expect(parentElement.style.transform, 'matrix(1, 0, 0, 1, 10, 10)');
     expect(parentElement.style.transformOrigin, '0px 0px 0px');
@@ -477,9 +476,9 @@ void _testContainer() {
     }
 
     final html.Element parentElement =
-        appShadowRoot.querySelector('flt-semantics');
+        appShadowRoot.querySelector('flt-semantics')!;
     final html.Element container =
-        appShadowRoot.querySelector('flt-semantics-container');
+        appShadowRoot.querySelector('flt-semantics-container')!;
 
     if (isMacOrIOS) {
       expect(parentElement.style.top, '0px');
@@ -550,12 +549,12 @@ void _testVerticalScrolling() {
   </sem-c>
 </sem>''');
 
-    final html.Element scrollable = findScrollable();
+    final html.Element? scrollable = findScrollable();
     expect(scrollable, isNotNull);
 
     // When there's less content than the available size the neutral scrollTop
     // is 0.
-    expect(scrollable.scrollTop, 0);
+    expect(scrollable!.scrollTop, 0);
 
     semantics().semanticsEnabled = false;
   });
@@ -574,7 +573,7 @@ void _testVerticalScrolling() {
     final Zone testZone = Zone.current;
 
     ui.window.onSemanticsAction =
-        (int id, ui.SemanticsAction action, ByteData args) {
+        (int id, ui.SemanticsAction action, ByteData? args) {
       idLogController.add(id);
       actionLogController.add(action);
       testZone.run(() {
@@ -620,7 +619,7 @@ void _testVerticalScrolling() {
   </sem-c>
 </sem>''');
 
-    final html.Element scrollable = findScrollable();
+    final html.Element? scrollable = findScrollable();
     expect(scrollable, isNotNull);
 
     // When there's more content than the available size the neutral scrollTop
@@ -633,7 +632,7 @@ void _testVerticalScrolling() {
       browserMaxScrollDiff = 1;
     }
 
-    expect(scrollable.scrollTop >= (10 - browserMaxScrollDiff), isTrue);
+    expect(scrollable!.scrollTop >= (10 - browserMaxScrollDiff), isTrue);
 
     scrollable.scrollTop = 20;
     expect(scrollable.scrollTop, 20);
@@ -702,12 +701,12 @@ void _testHorizontalScrolling() {
   </sem-c>
 </sem>''');
 
-    final html.Element scrollable = findScrollable();
+    final html.Element? scrollable = findScrollable();
     expect(scrollable, isNotNull);
 
     // When there's less content than the available size the neutral
     // scrollLeft is 0.
-    expect(scrollable.scrollLeft, 0);
+    expect(scrollable!.scrollLeft, 0);
 
     semantics().semanticsEnabled = false;
   });
@@ -753,7 +752,7 @@ void _testHorizontalScrolling() {
   </sem-c>
 </sem>''');
 
-    final html.Element scrollable = findScrollable();
+    final html.Element? scrollable = findScrollable();
     expect(scrollable, isNotNull);
 
     // When there's more content than the available size the neutral scrollTop
@@ -765,7 +764,7 @@ void _testHorizontalScrolling() {
         operatingSystem == OperatingSystem.macOs) {
       browserMaxScrollDiff = 1;
     }
-    expect(scrollable.scrollLeft >= (10 - browserMaxScrollDiff), isTrue);
+    expect(scrollable!.scrollLeft >= (10 - browserMaxScrollDiff), isTrue);
 
     scrollable.scrollLeft = 20;
     expect(scrollable.scrollLeft, 20);
@@ -835,7 +834,7 @@ void _testIncrementables() {
   <input aria-valuenow="1" aria-valuetext="d" aria-valuemax="2" aria-valuemin="1">
 </sem>''');
 
-    final html.InputElement input = appShadowRoot.querySelector('input');
+    final html.InputElement input = appShadowRoot.querySelector('input') as html.InputElement;
     input.value = '2';
     input.dispatchEvent(html.Event('change'));
 
@@ -869,7 +868,7 @@ void _testIncrementables() {
   <input aria-valuenow="1" aria-valuetext="d" aria-valuemax="1" aria-valuemin="0">
 </sem>''');
 
-    final html.InputElement input = appShadowRoot.querySelector('input');
+    final html.InputElement input = appShadowRoot.querySelector('input') as html.InputElement;
     input.value = '0';
     input.dispatchEvent(html.Event('change'));
 
@@ -963,7 +962,7 @@ void _testTextField() {
     semantics().updateSemantics(builder.build());
 
     final html.Element textField =
-        appShadowRoot.querySelector('input[data-semantics-role="text-field"]');
+        appShadowRoot.querySelector('input[data-semantics-role="text-field"]')!;
 
     expect(appShadowRoot.activeElement, isNot(textField));
 
@@ -1491,10 +1490,10 @@ void updateNode(
   String increasedValue = '',
   String decreasedValue = '',
   ui.TextDirection textDirection = ui.TextDirection.ltr,
-  Float64List transform,
-  Int32List childrenInTraversalOrder,
-  Int32List childrenInHitTestOrder,
-  Int32List additionalActions,
+  Float64List? transform,
+  Int32List? childrenInTraversalOrder,
+  Int32List? childrenInHitTestOrder,
+  Int32List? additionalActions,
 }) {
   transform ??= Float64List.fromList(Matrix4.identity().storage);
   childrenInTraversalOrder ??= Int32List(0);

lib/web_ui/test/engine/services/serialization_test.dart

@@ -2,7 +2,6 @@
 // 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:typed_data';
 
 import 'package:test/test.dart';

lib/web_ui/test/engine/surface/frame_timings_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
 import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
 import 'package:ui/src/engine.dart';
@@ -15,7 +14,7 @@ void main() {
 
 void testMain() {
   setUp(() async {
-    await initializeEngine();
+    initializeEngine();
   });
 
   test('collects frame timings', () async {

lib/web_ui/test/engine/surface/platform_view_test.dart

@@ -2,7 +2,6 @@
 // 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:async';
 import 'dart:html' as html;
 
@@ -22,7 +21,7 @@ void main() {
 }
 
 void testMain() {
-  PersistedPlatformView view;
+  late PersistedPlatformView view;
 
   group('PersistedPlatformView', () {
     setUp(() async {

lib/web_ui/test/engine/surface/shaders/normalized_gradient_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
 import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
 import 'package:ui/src/engine/html/shaders/normalized_gradient.dart';

lib/web_ui/test/engine/surface/shaders/shader_builder_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
 import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
 import 'package:ui/src/engine.dart';
@@ -25,7 +24,7 @@ void testMain() {
       ')';
 
   setUpAll(() async {
-    await webOnlyInitializeEngine();
+    webOnlyInitializeEngine();
   });
 
   group('Shader Declarations', () {

lib/web_ui/test/golden_tests/engine/canvas_draw_image_golden_test.dart

@@ -2,7 +2,6 @@
 // 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 'dart:math' as math;
 import 'dart:js_util' as js_util;
@@ -48,7 +47,7 @@ void testMain() async {
         }
       }
       sceneElement.append(engineCanvas.rootElement);
-      html.document.body.append(sceneElement);
+      html.document.body!.append(sceneElement);
       await matchGoldenFile('$fileName.png',
           region: region, maxDiffRatePercent: maxDiffRatePercent, write: write);
     } finally {
@@ -68,7 +67,7 @@ void testMain() async {
     final RecordingCanvas rc =
         RecordingCanvas(const Rect.fromLTRB(0, 0, 400, 300));
     rc.save();
-    rc.drawImage(createTestImage(), Offset(0, 0), new Paint());
+    rc.drawImage(createTestImage(), Offset(0, 0), SurfacePaint());
     rc.restore();
     await _checkScreenshot(rc, 'draw_image');
   });
@@ -79,7 +78,7 @@ void testMain() async {
     rc.save();
     rc.translate(50.0, 100.0);
     rc.rotate(math.pi / 4.0);
-    rc.drawImage(createTestImage(), Offset(0, 0), new Paint());
+    rc.drawImage(createTestImage(), Offset(0, 0), SurfacePaint());
     rc.restore();
     await _checkScreenshot(rc, 'draw_image_with_transform');
   });
@@ -90,7 +89,7 @@ void testMain() async {
     rc.save();
     rc.translate(50.0, 100.0);
     rc.rotate(math.pi / 4.0);
-    rc.drawImage(createTestImage(), Offset(30, 20), new Paint());
+    rc.drawImage(createTestImage(), Offset(30, 20), SurfacePaint());
     rc.restore();
     await _checkScreenshot(rc, 'draw_image_with_transform_and_offset');
   });
@@ -105,7 +104,7 @@ void testMain() async {
     double testWidth = testImage.width.toDouble();
     double testHeight = testImage.height.toDouble();
     rc.drawImageRect(testImage, Rect.fromLTRB(0, 0, testWidth, testHeight),
-        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), new Paint());
+        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), SurfacePaint());
     rc.restore();
     await _checkScreenshot(rc, 'draw_image_rect_with_transform');
   });
@@ -121,7 +120,7 @@ void testMain() async {
         testImage,
         Rect.fromLTRB(testWidth / 2, 0, testWidth, testHeight),
         Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight),
-        new Paint());
+        SurfacePaint());
     rc.restore();
     await _checkScreenshot(rc, 'draw_image_rect_with_source');
   });
@@ -139,7 +138,7 @@ void testMain() async {
         testImage,
         Rect.fromLTRB(testWidth / 2, 0, testWidth, testHeight),
         Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight),
-        new Paint());
+        SurfacePaint());
     rc.restore();
     await _checkScreenshot(rc, 'draw_image_rect_with_source_and_clip');
   });
@@ -157,7 +156,7 @@ void testMain() async {
         testImage,
         Rect.fromLTRB(testWidth / 2, 0, testWidth, testHeight),
         Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight),
-        new Paint());
+        SurfacePaint());
     rc.restore();
     await _checkScreenshot(rc, 'draw_image_rect_with_transform_source');
   });
@@ -172,11 +171,11 @@ void testMain() async {
     double testWidth = testImage.width.toDouble();
     double testHeight = testImage.height.toDouble();
     rc.drawImageRect(testImage, Rect.fromLTRB(0, 0, testWidth, testHeight),
-        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), new Paint());
+        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), SurfacePaint());
     rc.drawCircle(
         Offset(100, 100),
         50.0,
-        Paint()
+        SurfacePaint()
           ..strokeWidth = 3
           ..color = Color.fromARGB(128, 0, 0, 0));
     rc.restore();
@@ -195,11 +194,11 @@ void testMain() async {
     rc.drawCircle(
         Offset(100, 100),
         50.0,
-        Paint()
+        SurfacePaint()
           ..strokeWidth = 3
           ..color = Color.fromARGB(128, 0, 0, 0));
     rc.drawImageRect(testImage, Rect.fromLTRB(0, 0, testWidth, testHeight),
-        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), new Paint());
+        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), SurfacePaint());
     rc.restore();
     await _checkScreenshot(rc, 'draw_circle_below_image');
   });
@@ -215,11 +214,11 @@ void testMain() async {
     double testHeight = testImage.height.toDouble();
     rc.clipRect(Rect.fromLTRB(75, 75, 160, 160), ClipOp.intersect);
     rc.drawImageRect(testImage, Rect.fromLTRB(0, 0, testWidth, testHeight),
-        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), new Paint());
+        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), SurfacePaint());
     rc.drawCircle(
         Offset(100, 100),
         50.0,
-        Paint()
+        SurfacePaint()
           ..strokeWidth = 3
           ..color = Color.fromARGB(128, 0, 0, 0));
     rc.restore();
@@ -241,11 +240,11 @@ void testMain() async {
     rc.translate(-100, -100);
     rc.clipRect(Rect.fromLTRB(75, 75, 160, 160), ClipOp.intersect);
     rc.drawImageRect(testImage, Rect.fromLTRB(0, 0, testWidth, testHeight),
-        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), new Paint());
+        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), SurfacePaint());
     rc.drawCircle(
         Offset(100, 100),
         50.0,
-        Paint()
+        SurfacePaint()
           ..strokeWidth = 3
           ..color = Color.fromARGB(128, 0, 0, 0));
     rc.restore();
@@ -268,11 +267,11 @@ void testMain() async {
     rc.translate(-100, -100);
     rc.clipRect(Rect.fromLTRB(75, 75, 160, 160), ClipOp.intersect);
     rc.drawImageRect(testImage, Rect.fromLTRB(0, 0, testWidth, testHeight),
-        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), new Paint());
+        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), SurfacePaint());
     rc.drawCircle(
         Offset(100, 100),
         50.0,
-        Paint()
+        SurfacePaint()
           ..strokeWidth = 3
           ..color = Color.fromARGB(128, 0, 0, 0));
     rc.restore();
@@ -291,11 +290,11 @@ void testMain() async {
     double testHeight = testImage.height.toDouble();
     rc.clipRRect(RRect.fromLTRBR(75, 75, 160, 160, Radius.circular(5)));
     rc.drawImageRect(testImage, Rect.fromLTRB(0, 0, testWidth, testHeight),
-        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), Paint());
+        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), SurfacePaint());
     rc.drawCircle(
         Offset(100, 100),
         50.0,
-        Paint()
+        SurfacePaint()
           ..strokeWidth = 3
           ..color = Color.fromARGB(128, 0, 0, 0));
     rc.restore();
@@ -318,11 +317,11 @@ void testMain() async {
     path.lineTo(160, 160);
     rc.clipPath(path);
     rc.drawImageRect(testImage, Rect.fromLTRB(0, 0, testWidth, testHeight),
-        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), Paint());
+        Rect.fromLTRB(100, 30, 2 * testWidth, 2 * testHeight), SurfacePaint());
     rc.drawCircle(
         Offset(100, 100),
         50.0,
-        Paint()
+        SurfacePaint()
           ..strokeWidth = 3
           ..color = Color.fromARGB(128, 0, 0, 0));
     rc.restore();
@@ -349,10 +348,10 @@ void testMain() async {
     paragraph1.layout(const ParagraphConstraints(width: 400.0));
     rc.drawParagraph(paragraph1, const Offset(20, 100));
     rc.drawImageRect(testImage, Rect.fromLTRB(0, 0, testWidth, testHeight),
-        Rect.fromLTRB(100, 100, 200, 200), Paint());
+        Rect.fromLTRB(100, 100, 200, 200), SurfacePaint());
     rc.drawRect(
         Rect.fromLTWH(50, 50, 100, 200),
-        Paint()
+        SurfacePaint()
           ..strokeWidth = 3
           ..color = Color(0xA0000000));
     final Color cyan = Color(0xFF0097A7);
@@ -378,7 +377,7 @@ void testMain() async {
     Image testImage = createNineSliceImage();
     canvas.clipRect(Rect.fromLTWH(0, 0, 420, 200));
     canvas.drawImageNine(testImage, Rect.fromLTWH(20, 20, 20, 20),
-        Rect.fromLTWH(20, 20, 400, 400), Paint());
+        Rect.fromLTWH(20, 20, 400, 400), SurfacePaint());
     Picture picture = recorder.endRecording();
 
     final SurfaceSceneBuilder builder = SurfaceSceneBuilder();
@@ -387,8 +386,8 @@ void testMain() async {
     // Wrap in <flt-scene> so that our CSS selectors kick in.
     final html.Element sceneElement = html.Element.tag('flt-scene');
     try {
-      sceneElement.append(builder.build().webOnlyRootElement);
-      html.document.body.append(sceneElement);
+      sceneElement.append(builder.build().webOnlyRootElement!);
+      html.document.body!.append(sceneElement);
       await matchGoldenFile('draw_nine_slice.png',
           region: region, maxDiffRatePercent: 0);
     } finally {
@@ -411,7 +410,7 @@ void testMain() async {
     // of the image are 40x40. Drawing into a destination that is smaller
     // than that will not provide enough room to draw the center portion.
     canvas.drawImageNine(testImage, Rect.fromLTWH(20, 20, 20, 20),
-        Rect.fromLTWH(20, 20, 36, 36), Paint());
+        Rect.fromLTWH(20, 20, 36, 36), SurfacePaint());
     Picture picture = recorder.endRecording();
 
     final SurfaceSceneBuilder builder = SurfaceSceneBuilder();
@@ -420,8 +419,8 @@ void testMain() async {
     // Wrap in <flt-scene> so that our CSS selectors kick in.
     final html.Element sceneElement = html.Element.tag('flt-scene');
     try {
-      sceneElement.append(builder.build().webOnlyRootElement);
-      html.document.body.append(sceneElement);
+      sceneElement.append(builder.build().webOnlyRootElement!);
+      html.document.body!.append(sceneElement);
       await matchGoldenFile('draw_nine_slice_empty_center.png',
           region: region, maxDiffRatePercent: 0);
     } finally {
@@ -447,7 +446,7 @@ void testMain() async {
       ..lineTo(50, 30)
       ..lineTo(10, 30)
       ..close());
-    canvas.drawImage(createNineSliceImage(), Offset.zero, Paint());
+    canvas.drawImage(createNineSliceImage(), Offset.zero, SurfacePaint());
     await _checkScreenshot(canvas, 'draw_clipped_and_transformed_image',
         region: region, maxDiffRatePercent: 1.0);
   });
@@ -457,12 +456,12 @@ void testMain() async {
     final Rect region = const Rect.fromLTRB(0, 0, 200, 200);
     final RecordingCanvas canvas = RecordingCanvas(region);
     canvas.translate(10, 10);
-    canvas.drawImage(createTestImage(), Offset(0, 0), new Paint());
+    canvas.drawImage(createTestImage(), Offset(0, 0), SurfacePaint());
     Matrix4 transform = Matrix4.identity()
       ..setRotationY(0.8)
       ..setEntry(3, 2, 0.0005); // perspective
     canvas.transform(transform.storage);
-    canvas.drawImage(createTestImage(), Offset(0, 100), new Paint());
+    canvas.drawImage(createTestImage(), Offset(0, 100), SurfacePaint());
     await _checkScreenshot(canvas, 'draw_3d_image',
         region: region,
         maxDiffRatePercent: 6.0,
@@ -473,17 +472,17 @@ void testMain() async {
   test('Should render image with perspective inside clip area', () async {
     final Rect region = const Rect.fromLTRB(0, 0, 200, 200);
     final RecordingCanvas canvas = RecordingCanvas(region);
-    canvas.drawRect(region, Paint()..color = Color(0xFFE0E0E0));
+    canvas.drawRect(region, SurfacePaint()..color = Color(0xFFE0E0E0));
     canvas.translate(10, 10);
-    canvas.drawImage(createTestImage(), Offset(0, 0), new Paint());
+    canvas.drawImage(createTestImage(), Offset(0, 0), SurfacePaint());
     Matrix4 transform = Matrix4.identity()
       ..setRotationY(0.8)
       ..setEntry(3, 2, 0.0005); // perspective
     canvas.transform(transform.storage);
     canvas.clipRect(region, ClipOp.intersect);
-    canvas.drawRect(Rect.fromLTWH(0, 0, 100, 200), Paint()..color = Color(0x801080E0));
-    canvas.drawImage(createTestImage(), Offset(0, 100), new Paint());
-    canvas.drawRect(Rect.fromLTWH(50, 150, 50, 20), Paint()..color = Color(0x80000000));
+    canvas.drawRect(Rect.fromLTWH(0, 0, 100, 200), SurfacePaint()..color = Color(0x801080E0));
+    canvas.drawImage(createTestImage(), Offset(0, 100), SurfacePaint());
+    canvas.drawRect(Rect.fromLTWH(50, 150, 50, 20), SurfacePaint()..color = Color(0x80000000));
     await _checkScreenshot(canvas, 'draw_3d_image_clipped',
         region: region,
         maxDiffRatePercent: 5.0,
@@ -493,21 +492,21 @@ void testMain() async {
   test('Should render rect with perspective transform', () async {
     final Rect region = const Rect.fromLTRB(0, 0, 400, 400);
     final RecordingCanvas canvas = RecordingCanvas(region);
-    canvas.drawRect(region, Paint()..color = Color(0xFFE0E0E0));
+    canvas.drawRect(region, SurfacePaint()..color = Color(0xFFE0E0E0));
     canvas.translate(20, 20);
     canvas.drawRect(Rect.fromLTWH(0, 0, 100, 40),
-        Paint()..color = Color(0xFF000000));
+        SurfacePaint()..color = Color(0xFF000000));
     Matrix4 transform = Matrix4.identity()
       ..setRotationY(0.8)
       ..setEntry(3, 2, 0.001); // perspective
     canvas.transform(transform.storage);
     canvas.clipRect(region, ClipOp.intersect);
-    canvas.drawRect(Rect.fromLTWH(0, 60, 120, 40), Paint()..color = Color(0x801080E0));
-    canvas.drawRect(Rect.fromLTWH(300, 250, 120, 40), Paint()..color = Color(0x80E010E0));
+    canvas.drawRect(Rect.fromLTWH(0, 60, 120, 40), SurfacePaint()..color = Color(0x801080E0));
+    canvas.drawRect(Rect.fromLTWH(300, 250, 120, 40), SurfacePaint()..color = Color(0x80E010E0));
     canvas.drawRRect(RRect.fromRectAndRadius(Rect.fromLTWH(0, 120, 160, 40), Radius.circular(5)),
-        Paint()..color = Color(0x801080E0));
+        SurfacePaint()..color = Color(0x801080E0));
     canvas.drawRRect(RRect.fromRectAndRadius(Rect.fromLTWH(300, 320, 90, 40), Radius.circular(20)),
-        Paint()..color = Color(0x80E010E0));
+        SurfacePaint()..color = Color(0x80E010E0));
     await _checkScreenshot(canvas, 'draw_3d_rect_clipped',
         region: region,
         maxDiffRatePercent: 1.0,
@@ -517,22 +516,22 @@ void testMain() async {
   test('Should render color and ovals with perspective transform', () async {
     final Rect region = const Rect.fromLTRB(0, 0, 400, 400);
     final RecordingCanvas canvas = RecordingCanvas(region);
-    canvas.drawRect(region, Paint()..color = Color(0xFFFF0000));
+    canvas.drawRect(region, SurfacePaint()..color = Color(0xFFFF0000));
     canvas.drawColor(Color(0xFFE0E0E0), BlendMode.src);
     canvas.translate(20, 20);
     canvas.drawRect(Rect.fromLTWH(0, 0, 100, 40),
-        Paint()..color = Color(0xFF000000));
+        SurfacePaint()..color = Color(0xFF000000));
     Matrix4 transform = Matrix4.identity()
       ..setRotationY(0.8)
       ..setEntry(3, 2, 0.001); // perspective
     canvas.transform(transform.storage);
     canvas.clipRect(region, ClipOp.intersect);
     canvas.drawOval(Rect.fromLTWH(0, 120, 130, 40),
-        Paint()..color = Color(0x801080E0));
+        SurfacePaint()..color = Color(0x801080E0));
     canvas.drawOval(Rect.fromLTWH(300, 290, 90, 40),
-        Paint()..color = Color(0x80E010E0));
-    canvas.drawCircle(Offset(60, 240), 50, Paint()..color = Color(0x801080E0));
-    canvas.drawCircle(Offset(360, 370), 30, Paint()..color = Color(0x80E010E0));
+        SurfacePaint()..color = Color(0x80E010E0));
+    canvas.drawCircle(Offset(60, 240), 50, SurfacePaint()..color = Color(0x801080E0));
+    canvas.drawCircle(Offset(360, 370), 30, SurfacePaint()..color = Color(0x80E010E0));
     await _checkScreenshot(canvas, 'draw_3d_oval_clipped',
         region: region,
         maxDiffRatePercent: 1.0,
@@ -542,29 +541,29 @@ void testMain() async {
   test('Should render path with perspective transform', () async {
     final Rect region = const Rect.fromLTRB(0, 0, 400, 400);
     final RecordingCanvas canvas = RecordingCanvas(region);
-    canvas.drawRect(region, Paint()..color = Color(0xFFFF0000));
+    canvas.drawRect(region, SurfacePaint()..color = Color(0xFFFF0000));
     canvas.drawColor(Color(0xFFE0E0E0), BlendMode.src);
     canvas.translate(20, 20);
     canvas.drawRect(Rect.fromLTWH(0, 0, 100, 20),
-        Paint()..color = Color(0xFF000000));
+        SurfacePaint()..color = Color(0xFF000000));
     Matrix4 transform = Matrix4.identity()
       ..setRotationY(0.8)
       ..setEntry(3, 2, 0.001); // perspective
     canvas.transform(transform.storage);
     canvas.drawRect(Rect.fromLTWH(0, 120, 130, 40),
-        Paint()..color = Color(0x801080E0));
+        SurfacePaint()..color = Color(0x801080E0));
     canvas.drawOval(Rect.fromLTWH(300, 290, 90, 40),
-        Paint()..color = Color(0x80E010E0));
+        SurfacePaint()..color = Color(0x80E010E0));
     Path path = Path();
     path.moveTo(50, 50);
     path.lineTo(100, 50);
     path.lineTo(100, 100);
     path.close();
-    canvas.drawPath(path, Paint()..color = Color(0x801080E0));
+    canvas.drawPath(path, SurfacePaint()..color = Color(0x801080E0));
 
-    canvas.drawCircle(Offset(50, 50), 4, Paint()..color = Color(0xFF000000));
-    canvas.drawCircle(Offset(100, 100), 4, Paint()..color = Color(0xFF000000));
-    canvas.drawCircle(Offset(100, 50), 4, Paint()..color = Color(0xFF000000));
+    canvas.drawCircle(Offset(50, 50), 4, SurfacePaint()..color = Color(0xFF000000));
+    canvas.drawCircle(Offset(100, 100), 4, SurfacePaint()..color = Color(0xFF000000));
+    canvas.drawCircle(Offset(100, 50), 4, SurfacePaint()..color = Color(0xFF000000));
     await _checkScreenshot(canvas, 'draw_3d_path',
         region: region,
         maxDiffRatePercent: 1.0,
@@ -574,30 +573,30 @@ void testMain() async {
   test('Should render path with perspective transform', () async {
     final Rect region = const Rect.fromLTRB(0, 0, 400, 400);
     final RecordingCanvas canvas = RecordingCanvas(region);
-    canvas.drawRect(region, Paint()..color = Color(0xFFFF0000));
+    canvas.drawRect(region, SurfacePaint()..color = Color(0xFFFF0000));
     canvas.drawColor(Color(0xFFE0E0E0), BlendMode.src);
     canvas.translate(20, 20);
     canvas.drawRect(Rect.fromLTWH(0, 0, 100, 20),
-        Paint()..color = Color(0xFF000000));
+        SurfacePaint()..color = Color(0xFF000000));
     Matrix4 transform = Matrix4.identity()
       ..setRotationY(0.8)
       ..setEntry(3, 2, 0.001); // perspective
     canvas.transform(transform.storage);
     //canvas.clipRect(region, ClipOp.intersect);
     canvas.drawRect(Rect.fromLTWH(0, 120, 130, 40),
-        Paint()..color = Color(0x801080E0));
+        SurfacePaint()..color = Color(0x801080E0));
     canvas.drawOval(Rect.fromLTWH(300, 290, 90, 40),
-        Paint()..color = Color(0x80E010E0));
+        SurfacePaint()..color = Color(0x80E010E0));
     Path path = Path();
     path.moveTo(50, 50);
     path.lineTo(100, 50);
     path.lineTo(100, 100);
     path.close();
-    canvas.drawPath(path, Paint()..color = Color(0x801080E0));
+    canvas.drawPath(path, SurfacePaint()..color = Color(0x801080E0));
 
-    canvas.drawCircle(Offset(50, 50), 4, Paint()..color = Color(0xFF000000));
-    canvas.drawCircle(Offset(100, 100), 4, Paint()..color = Color(0xFF000000));
-    canvas.drawCircle(Offset(100, 50), 4, Paint()..color = Color(0xFF000000));
+    canvas.drawCircle(Offset(50, 50), 4, SurfacePaint()..color = Color(0xFF000000));
+    canvas.drawCircle(Offset(100, 100), 4, SurfacePaint()..color = Color(0xFF000000));
+    canvas.drawCircle(Offset(100, 50), 4, SurfacePaint()..color = Color(0xFF000000));
     await _checkScreenshot(canvas, 'draw_3d_path_clipped',
         region: region,
         maxDiffRatePercent: 1.0,

lib/web_ui/test/golden_tests/engine/canvas_rect_golden_test.dart

@@ -2,7 +2,6 @@
 // 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:test/bootstrap/browser.dart';
@@ -19,7 +18,7 @@ void main() {
 void testMain() async {
   final Rect region = Rect.fromLTWH(0, 0, 150, 420);
 
-  BitmapCanvas canvas;
+  late BitmapCanvas canvas;
 
   setUp(() {
     canvas = BitmapCanvas(region, RenderStrategy());
@@ -33,7 +32,7 @@ void testMain() async {
 
     paintRects(canvas);
 
-    html.document.body.append(canvas.rootElement);
+    html.document.body!.append(canvas.rootElement);
     await matchGoldenFile('canvas_rect_flipped.png', region: region);
   });
 }

lib/web_ui/test/golden_tests/engine/canvas_rrect_golden_test.dart

@@ -2,7 +2,6 @@
 // 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:test/bootstrap/browser.dart';
@@ -19,7 +18,7 @@ void main() {
 void testMain() async {
   final Rect region = Rect.fromLTWH(8, 8, 500, 100); // Compensate for old scuba tester padding
 
-  BitmapCanvas canvas;
+  late BitmapCanvas canvas;
 
   final SurfacePaintData niceRRectPaint = SurfacePaintData()
     ..color = const Color.fromRGBO(250, 186, 218, 1.0) // #fabada
@@ -48,7 +47,7 @@ void testMain() async {
           niceRRectPaint);
     }
 
-    html.document.body.append(canvas.rootElement);
+    html.document.body!.append(canvas.rootElement);
     await matchGoldenFile('canvas_rrect_round_square.png', region: region);
   });
 
@@ -61,7 +60,7 @@ void testMain() async {
           Radius.circular(30)),
       niceRRectPaint);
     canvas.drawPath(Path()..moveTo(0, 0)..lineTo(20, 0), niceRRectPaint);
-    html.document.body.append(canvas.rootElement);
+    html.document.body!.append(canvas.rootElement);
     await matchGoldenFile('canvas_rrect_flipped.png',
         region: Rect.fromLTWH(0, 0, 100, 200));
   });
@@ -78,7 +77,7 @@ void testMain() async {
       canvas.drawRRect(rrect, niceRRectPaint);
     }
 
-    html.document.body.append(canvas.rootElement);
+    html.document.body!.append(canvas.rootElement);
     await matchGoldenFile('canvas_rrect_overlapping_radius.png', region: region);
   });
 
@@ -101,7 +100,7 @@ void testMain() async {
       canvas.drawDRRect(outerRRect, innerRRect, niceRRectPaint);
     }
 
-    html.document.body.append(canvas.rootElement);
+    html.document.body!.append(canvas.rootElement);
     await matchGoldenFile('canvas_drrect_overlapping_radius.png', region: region);
   });
 }

lib/web_ui/test/golden_tests/engine/canvas_stroke_joins_golden_test.dart

@@ -2,7 +2,6 @@
 // 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:test/bootstrap/browser.dart';
@@ -19,7 +18,7 @@ void main() {
 void testMain() async {
   final Rect region = Rect.fromLTWH(0, 0, 300, 300);
 
-  BitmapCanvas canvas;
+  late BitmapCanvas canvas;
 
   setUp(() {
     canvas = BitmapCanvas(region, RenderStrategy());
@@ -33,7 +32,7 @@ void testMain() async {
 
     paintStrokeJoins(canvas);
 
-    html.document.body.append(canvas.rootElement);
+    html.document.body!.append(canvas.rootElement);
     await matchGoldenFile('canvas_stroke_joins.png', region: region);
   });
 

lib/web_ui/test/golden_tests/engine/canvas_stroke_rects_golden_test.dart

@@ -2,7 +2,6 @@
 // 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 'dart:math' as math;
 
@@ -20,7 +19,7 @@ void main() {
 void testMain() async {
   final Rect region = Rect.fromLTWH(0, 0, 300, 300);
 
-  BitmapCanvas canvas;
+  late BitmapCanvas canvas;
 
   setUp(() {
     canvas = BitmapCanvas(region, RenderStrategy());
@@ -34,7 +33,7 @@ void testMain() async {
 
     paintSideBySideRects(canvas);
 
-    html.document.body.append(canvas.rootElement);
+    html.document.body!.append(canvas.rootElement);
     await matchGoldenFile('canvas_stroke_rects.png', region: region);
   });
 

lib/web_ui/test/golden_tests/engine/canvas_winding_rule_test.dart

@@ -2,7 +2,6 @@
 // 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:test/bootstrap/browser.dart';
@@ -19,7 +18,7 @@ void main() {
 void testMain() async {
   final Rect region = Rect.fromLTWH(0, 0, 500, 500);
 
-  BitmapCanvas canvas;
+  late BitmapCanvas canvas;
 
   setUp(() {
     canvas = BitmapCanvas(region, RenderStrategy());
@@ -31,7 +30,7 @@ void testMain() async {
 
   test('draws paths using nonzero and evenodd winding rules', () async {
     paintPaths(canvas);
-    html.document.body.append(canvas.rootElement);
+    html.document.body!.append(canvas.rootElement);
     await matchGoldenFile('canvas_path_winding.png', region: region);
   });
 

lib/web_ui/test/golden_tests/engine/clip_op_golden_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.6
 import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
 import 'package:ui/ui.dart';
@@ -23,7 +22,7 @@ void testMain() async {
     final Rect region = const Rect.fromLTRB(0, 0, 400, 300);
     final RecordingCanvas canvas = RecordingCanvas(region);
     final Rect titleRect = Rect.fromLTWH(20, 0, 50, 20);
-    final Paint paint = Paint()
+    final SurfacePaint paint = SurfacePaint()
       ..style = PaintingStyle.stroke
       ..color = const Color(0xff000000)
       ..strokeWidth = 1;

lib/web_ui/test/golden_tests/engine/conic_golden_test.dart

@@ -2,7 +2,6 @@
 // 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:test/bootstrap/browser.dart';
@@ -25,13 +24,13 @@ void testMain() async {
         RenderStrategy());
     final RecordingCanvas canvas = RecordingCanvas(canvasBounds);
 
-    Paint paint = Paint()
+    SurfacePaint paint = SurfacePaint()
       ..color = const Color(0x7F7F7F7F)
       ..style = PaintingStyle.fill;
 
     canvas.drawPath(path, paint);
 
-    paint = Paint()
+    paint = SurfacePaint()
       ..strokeWidth = 2.0
       ..color = const Color(0xFF7F007F)
       ..style = PaintingStyle.stroke;
@@ -39,7 +38,7 @@ void testMain() async {
     canvas.drawPath(path, paint);
     canvas.endRecording();
 
-    html.document.body.append(bitmapCanvas.rootElement);
+    html.document.body!.append(bitmapCanvas.rootElement);
     canvas.apply(bitmapCanvas, canvasBounds);
     await matchGoldenFile('$scubaFileName.png', region: region);
     bitmapCanvas.rootElement.remove();

lib/web_ui/test/golden_tests/engine/shadow_golden_test.dart

@@ -2,7 +2,6 @@
 // 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:test/bootstrap/browser.dart';
@@ -23,7 +22,7 @@ void main() {
 void testMain() async {
   final Rect region = Rect.fromLTWH(0, 0, 550, 300);
 
-  SurfaceSceneBuilder builder;
+  late SurfaceSceneBuilder builder;
 
   setUpStableTestFonts();
 
@@ -32,7 +31,7 @@ void testMain() async {
   });
 
   void _paintShapeOutline() {
-    final EnginePictureRecorder recorder = PictureRecorder();
+    final EnginePictureRecorder recorder = EnginePictureRecorder();
     final RecordingCanvas canvas = recorder.beginRecording(Rect.largest);
     canvas.drawRect(
       const Rect.fromLTRB(0.0, 0.0, 20.0, 20.0),
@@ -81,7 +80,7 @@ void testMain() async {
       ..addRect(const Rect.fromLTRB(0, 0, 20, 20));
     builder.pushOffset(offset.dx, offset.dy);
 
-    final EnginePictureRecorder recorder = PictureRecorder();
+    final EnginePictureRecorder recorder = EnginePictureRecorder();
     final RecordingCanvas canvas = recorder.beginRecording(Rect.largest);
     canvas
         .debugEnforceArbitraryPaint(); // make sure DOM canvas doesn't take over
@@ -107,7 +106,7 @@ void testMain() async {
       ..close();
     builder.pushOffset(offset.dx, offset.dy);
 
-    final EnginePictureRecorder recorder = PictureRecorder();
+    final EnginePictureRecorder recorder = EnginePictureRecorder();
     final RecordingCanvas canvas = recorder.beginRecording(Rect.largest);
     canvas
         .debugEnforceArbitraryPaint(); // make sure DOM canvas doesn't take over
@@ -157,8 +156,8 @@ void testMain() async {
 
       builder.pop();
 
-      final html.Element sceneElement = builder.build().webOnlyRootElement;
-      html.document.body.append(sceneElement);
+      final html.Element sceneElement = builder.build().webOnlyRootElement!;
+      html.document.body!.append(sceneElement);
 
       await matchGoldenFile(
         'shadows.png',

lib/web_ui/test/text/font_collection_test.dart

@@ -2,7 +2,6 @@
 // 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:test/bootstrap/browser.dart';
@@ -16,7 +15,7 @@ void main() {
 
 void testMain() {
   group('$FontManager', () {
-    FontManager fontManager;
+    late FontManager fontManager;
     const String _testFontUrl = 'packages/ui/assets/ahem.ttf';
 
     setUp(() {
@@ -24,7 +23,7 @@ void testMain() {
     });
 
     tearDown(() {
-      html.document.fonts.clear();
+      html.document.fonts!.clear();
     });
 
     group('regular special characters', () {
@@ -35,9 +34,9 @@ void testMain() {
         fontManager.registerAsset(
             _testFontFamily, 'url($_testFontUrl)', const <String, String>{});
         await fontManager.ensureFontsLoaded();
-        html.document.fonts
+        html.document.fonts!
             .forEach((html.FontFace f, html.FontFace f2, html.FontFaceSet s) {
-          fontFamilyList.add(f.family);
+          fontFamilyList.add(f.family!);
         });
 
         expect(fontFamilyList.length, equals(1));
@@ -53,9 +52,9 @@ void testMain() {
         fontManager.registerAsset(
             _testFontFamily, 'url($_testFontUrl)', const <String, String>{});
         await fontManager.ensureFontsLoaded();
-        html.document.fonts
+        html.document.fonts!
             .forEach((html.FontFace f, html.FontFace f2, html.FontFaceSet s) {
-          fontFamilyList.add(f.family);
+          fontFamilyList.add(f.family!);
         });
 
         expect(fontFamilyList.length, equals(1));
@@ -73,9 +72,9 @@ void testMain() {
         fontManager.registerAsset(
             _testFontFamily, 'url($_testFontUrl)', const <String, String>{});
         await fontManager.ensureFontsLoaded();
-        html.document.fonts
+        html.document.fonts!
             .forEach((html.FontFace f, html.FontFace f2, html.FontFaceSet s) {
-          fontFamilyList.add(f.family);
+          fontFamilyList.add(f.family!);
         });
 
         expect(fontFamilyList.length, equals(1));
@@ -93,9 +92,9 @@ void testMain() {
         fontManager.registerAsset(
             _testFontFamily, 'url($_testFontUrl)', const <String, String>{});
         await fontManager.ensureFontsLoaded();
-        html.document.fonts
+        html.document.fonts!
             .forEach((html.FontFace f, html.FontFace f2, html.FontFaceSet s) {
-          fontFamilyList.add(f.family);
+          fontFamilyList.add(f.family!);
         });
 
         if (browserEngine != BrowserEngine.firefox) {
@@ -119,9 +118,9 @@ void testMain() {
         fontManager.registerAsset(
             _testFontFamily, 'url($_testFontUrl)', const <String, String>{});
         await fontManager.ensureFontsLoaded();
-        html.document.fonts
+        html.document.fonts!
             .forEach((html.FontFace f, html.FontFace f2, html.FontFaceSet s) {
-          fontFamilyList.add(f.family);
+          fontFamilyList.add(f.family!);
         });
 
         if (browserEngine != BrowserEngine.firefox) {
@@ -145,9 +144,9 @@ void testMain() {
         fontManager.registerAsset(
             _testFontFamily, 'url($_testFontUrl)', const <String, String>{});
         await fontManager.ensureFontsLoaded();
-        html.document.fonts
+        html.document.fonts!
             .forEach((html.FontFace f, html.FontFace f2, html.FontFaceSet s) {
-          fontFamilyList.add(f.family);
+          fontFamilyList.add(f.family!);
         });
 
         if (browserEngine != BrowserEngine.firefox) {
@@ -172,9 +171,9 @@ void testMain() {
         fontManager.registerAsset(
             testFontFamily, 'url($_testFontUrl)', const <String, String>{});
         await fontManager.ensureFontsLoaded();
-        html.document.fonts
+        html.document.fonts!
             .forEach((html.FontFace f, html.FontFace f2, html.FontFaceSet s) {
-          fontFamilyList.add(f.family);
+          fontFamilyList.add(f.family!);
         });
 
         if (browserEngine != BrowserEngine.firefox) {

lib/web_ui/test/text/font_loading_test.dart

@@ -2,7 +2,6 @@
 // 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:async';
 import 'dart:convert';
 import 'dart:html' as html;
@@ -23,7 +22,7 @@ void testMain() async {
     const String _testFontUrl = 'packages/ui/assets/ahem.ttf';
 
     tearDown(() {
-      html.document.fonts.clear();
+      html.document.fonts!.clear();
     });
 
     test('surfaces error from invalid font buffer', () async {
@@ -53,7 +52,7 @@ void testMain() async {
             browserEngine == BrowserEngine.webkit));
 
     test('loading font should clear measurement caches', () async {
-      final ui.ParagraphStyle style = ui.ParagraphStyle();
+      final EngineParagraphStyle style = EngineParagraphStyle();
       final ui.ParagraphConstraints constraints =
           ui.ParagraphConstraints(width: 30.0);
 
@@ -61,7 +60,7 @@ void testMain() async {
       domBuilder.addText('test');
       // Triggers the measuring and verifies the result has been cached.
       domBuilder.build().layout(constraints);
-      expect(TextMeasurementService.rulerManager.rulers.length, 1);
+      expect(TextMeasurementService.rulerManager!.rulers.length, 1);
 
       final CanvasParagraphBuilder canvasBuilder = CanvasParagraphBuilder(style);
       canvasBuilder.addText('test');
@@ -79,7 +78,7 @@ void testMain() async {
 
       // Verifies the font is loaded, and the cache is cleaned.
       expect(_containsFontFamily('Blehm'), isTrue);
-      expect(TextMeasurementService.rulerManager.rulers.length, 0);
+      expect(TextMeasurementService.rulerManager!.rulers.length, 0);
       expect(Spanometer.rulers.length, 0);
     },
         // TODO(nurhan): https://github.com/flutter/flutter/issues/56702
@@ -88,13 +87,13 @@ void testMain() async {
             browserEngine == BrowserEngine.webkit));
 
     test('loading font should send font change message', () async {
-      final ui.PlatformMessageCallback oldHandler = ui.window.onPlatformMessage;
-      String actualName;
-      String message;
-      window.onPlatformMessage = (String name, ByteData data,
-          ui.PlatformMessageResponseCallback callback) {
+      final ui.PlatformMessageCallback? oldHandler = ui.window.onPlatformMessage;
+      String? actualName;
+      String? message;
+      window.onPlatformMessage = (String name, ByteData? data,
+          ui.PlatformMessageResponseCallback? callback) {
         actualName = name;
-        final buffer = data.buffer;
+        final buffer = data!.buffer;
         final Uint8List list =
             buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
         message = utf8.decode(list);
@@ -120,7 +119,7 @@ void testMain() async {
 
 bool _containsFontFamily(String family) {
   bool found = false;
-  html.document.fonts.forEach((html.FontFace fontFace,
+  html.document.fonts!.forEach((html.FontFace fontFace,
       html.FontFace fontFaceAgain, html.FontFaceSet fontFaceSet) {
     if (fontFace.family == family) {
       found = true;