Ignore dart:html deprecation for now (#2583)

See https://github.com/flutter/samples/issues/2582

web/samples_index/lib/src/carousel.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file
 
+// TODO(kevmoo): https://github.com/flutter/samples/issues/2582
+// ignore: deprecated_member_use
 import 'dart:html';
 
 class Carousel {

web/samples_index/web/description.dart

@@ -1,3 +1,5 @@
+// TODO(kevmoo): https://github.com/flutter/samples/issues/2582
+// ignore: deprecated_member_use
 import 'dart:html';
 
 import 'package:mdc_web/mdc_web.dart';

web/samples_index/web/main.dart

@@ -1,3 +1,5 @@
+// TODO(kevmoo): https://github.com/flutter/samples/issues/2582
+// ignore: deprecated_member_use
 import 'dart:html';
 
 import 'package:mdc_web/mdc_web.dart';