TF-292 Fix two scroll bars for medium sized screens

core/lib/presentation/utils/shims/dart_ui.dart

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+// Copyright 2019 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.
+
+/// This file shims dart:ui in web-only scenarios, getting rid of the need to
+/// suppress analyzer warnings.
+
+// TODO(): flutter/flutter#55000 Remove this file once web-only dart:ui APIs
+// are exposed from a dedicated place.
+export 'dart_ui_fake.dart' if (dart.library.html) 'dart_ui_real.dart';

core/lib/presentation/utils/shims/dart_ui_fake.dart

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+// Copyright 2019 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.
+
+// Fake interface for the logic that this package needs from (web-only) dart:ui.
+// This is conditionally exported so the analyzer sees these methods as available.
+
+/// Shim for web_ui engine.PlatformViewRegistry
+/// https://github.com/flutter/engine/blob/master/lib/web_ui/lib/ui.dart#L62
+// ignore: camel_case_types
+class platformViewRegistry {
+  /// Shim for registerViewFactory
+  /// https://github.com/flutter/engine/blob/master/lib/web_ui/lib/ui.dart#L72
+  static void registerViewFactory(
+      String viewTypeId, dynamic Function(int viewId) viewFactory) {}
+}
+
+/// Signature of callbacks that have no arguments and return no data.
+typedef VoidCallback = void Function();
+
+dynamic get window => null;

core/lib/presentation/utils/shims/dart_ui_real.dart

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+// Copyright 2019 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.
+
+export 'dart:ui';