Add shim for dart:ui (increase Pub score)

lib/shims/dart_ui.dart

@@ -0,0 +1,10 @@
+// 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';

lib/shims/dart_ui_fake.dart

@@ -0,0 +1,19 @@
+// 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();

lib/shims/dart_ui_real.dart

@@ -0,0 +1,5 @@
+// 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';

lib/src/widgets/iframe_web.dart

@@ -1,13 +1,13 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_html/html_parser.dart';
+import 'package:flutter_html/shims/dart_ui.dart' as ui;
 import 'package:flutter_html/src/replaced_element.dart';
 import 'package:flutter_html/src/utils.dart';
 import 'package:flutter_html/style.dart';
 import 'package:webview_flutter/webview_flutter.dart';
 import 'package:html/dom.dart' as dom;
 // ignore: avoid_web_libraries_in_flutter
 import 'dart:html' as html;
-import 'dart:ui' as ui;
 
 /// [IframeContentElement is a [ReplacedElement] with web content.
 class IframeContentElement extends ReplacedElement {