Repository: flutter
Issue: Web API does not match public fields of `dart:ui`
Labels: platform-web,P2,team-web,triaged-web

The web engine uses `api_conform_test.dart` to ensure the `dart:ui` API matches the `web_ui` API. This test validates that the constructors and methods of the APIs match, but it does not validate public fields. Because of this blind spot, the `web_ui` API is missing various public fields from `dart:ui`.

## Steps to Reproduce

1. Use `git apply` to apply the [attached patch](https://github.com/flutter/flutter/files/10748611/api_conform_test_field_check.patch) that will modify the `api_conform_test.dart` file to validate public fields
    * The test can likely be further modified to be stricter or to allow more variance, but this version validates that field exists, the type matches (by name), whether the field is modifiable (`final` or `const`) matches, and whether the fields are both static or instance fields
2. Run `dart test test/api_conform_test.dart` from the `/web_sdk` folder

**Expected results:** <!-- what did you want to see? -->
When running the modified test, the test should pass and you should get no warnings.

**Actual results:** <!-- what did you see? -->
The modified test returns the following mismatched fields (at time of filing the issue):

```
Warning: lib/ui/ui.dart Image.width is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart Image.height is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart FrameInfo.duration is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart FrameInfo.image is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart PathMetric.length is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart PathMetric.isClosed is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart PathMetric.contourIndex is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart PictureRasterizationException.message is missing from lib/web_ui/ui.dart.
Warning: PictureRasterizationException.stack can be modified in ui but not in web_ui
Warning: lib/ui/ui.dart RootIsolateToken.instance is missing from lib/web_ui/ui.dart.
Warning: PlatformConfiguration.defaultRouteName type mismatch:
  lib/ui/ui.dart     : String?
  lib/web_ui/ui.dart : String
Warning: lib/ui/ui.dart WindowPadding.left is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart WindowPadding.top is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart WindowPadding.right is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart WindowPadding.bottom is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart LineMetrics.hardBreak is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart LineMetrics.ascent is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart LineMetrics.descent is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart LineMetrics.unscaledAscent is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart LineMetrics.height is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart LineMetrics.width is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart LineMetrics.left is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart LineMetrics.baseline is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart LineMetrics.lineNumber is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart FlutterView.viewId is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart FlutterView.platformDispatcher is missing from lib/web_ui/ui.dart.
Warning: lib/ui/ui.dart FrameData.frameNumber is missing from lib/web_ui/ui.dart.
```