Add @proxy to annotations.dart - remove package:meta.

pkg/meta/lib/meta.dart

-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-/**
- * Constants for use in metadata annotations such as
- * `@proxy`.
- *
- * See also `@deprecated` and `@override` in the `dart:core` library.
- *
- * Annotations provide semantic information
- * that tools can use to provide a better user experience.
- * For example, an IDE might not autocomplete
- * the name of a function that's been marked `@deprecated`,
- * or it might display the function's name differently.
- *
- * For information on installing and importing this library, see the
- * [meta package on pub.dartlang.org]
- * (http://pub.dartlang.org/packages/meta).
- * For examples of using annotations, see
- * [Metadata](https://www.dartlang.org/docs/dart-up-and-running/contents/ch02.html#ch02-metadata)
- * in the language tour.
- */
-library meta;
-
-/**
- * An annotation used to mark a class that should be considered to implement
- * every possible getter, setter and method. Tools can use this annotation to
- * suppress warnings when there is no explicit implementation of a referenced
- * member. Tools should provide a hint if this annotation is applied to a class
- * that does not implement or inherit an implementation of the method
- * [:noSuchMethod:] (other than the implementation in [Object]). Note that
- * classes are not affected by the use of this annotation on a supertype.
- */
-const proxy = const _Proxy();
-
-class _Proxy {
-  const _Proxy();
-}