opt out dart:ui from nnbd (flutter#16473)

* opt out dart:ui from nnbd

* Annotate tests as well

lib/ui/channel_buffers.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 /// A saved platform message for a channel with its callback.

lib/ui/compositing.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 /// An opaque object representing a composited scene.

lib/ui/fixtures/ui_test.dart

@@ -1,3 +1,4 @@
+// @dart = 2.6
 // Copyright 2013 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.

lib/ui/geometry.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 /// Base class for [Size] and [Offset], which are both ways to describe

lib/ui/hash_codes.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 class _HashEnd { const _HashEnd(); }

lib/ui/hooks.dart

@@ -4,6 +4,7 @@
 
 // TODO(dnfield): Remove unused_import ignores when https://github.com/dart-lang/sdk/issues/35164 is resolved.
 
+// @dart = 2.6
 part of dart.ui;
 
 // ignore: unused_element

lib/ui/isolate_name_server.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 /// Static methods to allow for simple sharing of [SendPort]s across [Isolate]s.

lib/ui/lerp.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 /// Linearly interpolate between two numbers.

lib/ui/natives.dart

@@ -4,6 +4,7 @@
 
 // TODO(dnfield): remove unused_element ignores when https://github.com/dart-lang/sdk/issues/35164 is resolved.
 
+// @dart = 2.6
 part of dart.ui;
 
 // Corelib 'print' implementation.

lib/ui/painting.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 // Some methods in this file assert that their arguments are not null. These

lib/ui/plugins.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 /// A wrapper for a raw callback handle.

lib/ui/pointer.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 /// How the pointer has changed since the last report.

lib/ui/semantics.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 /// The possible actions that can be conveyed from the operating system

lib/ui/text.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 /// Whether to slant the glyphs in the font

lib/ui/ui.dart

@@ -9,6 +9,7 @@
 /// This library exposes the lowest-level services that Flutter frameworks use
 /// to bootstrap applications, such as classes for driving the input, graphics
 /// text, layout, and rendering subsystems.
+// @dart = 2.6
 library dart.ui;
 
 import 'dart:_internal' hide Symbol; // ignore: import_internal_library, unused_import

lib/ui/window.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of dart.ui;
 
 /// Signature of callbacks that have no arguments and return no data.

lib/web_ui/dev/browser.dart

@@ -2,6 +2,7 @@
 // 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:io';

lib/web_ui/dev/build.dart

@@ -2,6 +2,7 @@
 // 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 'package:args/command_runner.dart';

lib/web_ui/dev/chrome.dart

@@ -2,6 +2,7 @@
 // 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:io';
 

lib/web_ui/dev/chrome_installer.dart

@@ -2,6 +2,7 @@
 // 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:io' as io;
 
 import 'package:args/args.dart';

lib/web_ui/dev/clean.dart

@@ -2,6 +2,7 @@
 // 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:io' as io;
 

lib/web_ui/dev/common.dart

@@ -2,6 +2,7 @@
 // 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:io' as io;
 
 import 'package:args/args.dart';

lib/web_ui/dev/edge.dart

@@ -2,6 +2,7 @@
 // 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:io';
 

lib/web_ui/dev/edge_installation.dart

@@ -2,6 +2,7 @@
 // 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:io' as io;
 

lib/web_ui/dev/environment.dart

@@ -2,6 +2,7 @@
 // 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:io' as io;
 import 'package:path/path.dart' as pathlib;
 

lib/web_ui/dev/felt.dart

@@ -2,6 +2,7 @@
 // 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:io' as io;
 
 import 'package:args/command_runner.dart';

lib/web_ui/dev/firefox.dart

@@ -2,6 +2,7 @@
 // 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:io';
 

lib/web_ui/dev/firefox_installer.dart

@@ -1,6 +1,7 @@
 // Copyright 2013 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.
+// @dart = 2.6
 import 'dart:io' as io;
 
 import 'package:args/args.dart';

lib/web_ui/dev/firefox_installer_test.dart

@@ -4,6 +4,7 @@
 
 @TestOn('vm && linux')
 
+// @dart = 2.6
 import 'dart:io' as io;
 
 import 'package:path/path.dart' as path;

lib/web_ui/dev/goldens.dart

@@ -1,6 +1,7 @@
 // Copyright 2013 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.
+// @dart = 2.6
 import 'dart:io' as io;
 import 'package:image/image.dart';
 import 'package:meta/meta.dart';

lib/web_ui/dev/licenses.dart

@@ -2,6 +2,7 @@
 // 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:io' as io;
 
 import 'package:args/command_runner.dart';

lib/web_ui/dev/safari.dart

@@ -2,6 +2,7 @@
 // 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:io';
 

lib/web_ui/dev/safari_installation.dart

@@ -2,6 +2,7 @@
 // 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:io' as io;
 

lib/web_ui/dev/supported_browsers.dart

@@ -2,6 +2,7 @@
 // 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_api/src/backend/runtime.dart';
 
 import 'browser.dart';

lib/web_ui/dev/test_platform.dart

@@ -2,6 +2,7 @@
 // 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:io';

lib/web_ui/dev/test_runner.dart

@@ -2,6 +2,7 @@
 // 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:io' as io;
 

lib/web_ui/dev/utils.dart

@@ -2,6 +2,7 @@
 // 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:io' as io;
 

lib/web_ui/lib/src/engine.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 library engine;
 
 import 'dart:async';

lib/web_ui/lib/src/engine/alarm_clock.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// A function that returns current system time.

lib/web_ui/lib/src/engine/assets.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// This class downloads assets over the network.

lib/web_ui/lib/src/engine/bitmap_canvas.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// A raw HTML canvas that is directly written to.

lib/web_ui/lib/src/engine/browser_detection.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// The HTML engine used by the current browser.

lib/web_ui/lib/src/engine/browser_location.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 // TODO(mdebbar): add other strategies.

lib/web_ui/lib/src/engine/canvas_pool.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// Allocates and caches 0 or more canvas(s) for [BitmapCanvas].

lib/web_ui/lib/src/engine/clipboard.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// Handles clipboard related platform messages.

lib/web_ui/lib/src/engine/color_filter.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// A description of a color filter to apply when drawing a shape or compositing

lib/web_ui/lib/src/engine/compositor/canvas.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// A Dart wrapper around Skia's SKCanvas.

lib/web_ui/lib/src/engine/compositor/canvas_kit_canvas.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// An implementation of [ui.Canvas] that is backed by a CanvasKit canvas.

lib/web_ui/lib/src/engine/compositor/color_filter.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// A [ui.ColorFilter] backed by Skia's [SkColorFilter].

lib/web_ui/lib/src/engine/compositor/embedded_views.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart = 2.6
 part of engine;
 
 /// This composites HTML views into the [ui.Scene].