Make PlatformSelector use boolean_selector.

lib/src/backend/platform_selector/token.dart

Index: lib/src/backend/platform_selector/token.dart
diff --git a/lib/src/backend/platform_selector/token.dart b/lib/src/backend/platform_selector/token.dart
deleted file mode 100644
index 759999f5523d03d065cf819e7a7e29617299e927..0000000000000000000000000000000000000000
--- a/lib/src/backend/platform_selector/token.dart
+++ /dev/null
@@ -1,70 +0,0 @@
-// Copyright (c) 2015, 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.
-
-import 'package:source_span/source_span.dart';
-
-/// A token in a platform selector.
-class Token {
-  /// The type of the token.
-  final TokenType type;
-
-  /// The span indicating where this token came from.
-  ///
-  /// This is a [FileSpan] because the tokens are parsed from a single
-  /// continuous string, but the string itself isn't actually a file. It might
-  /// come from a statically-parsed annotation or from a parameter.
-  final FileSpan span;
-
-  Token(this.type, this.span);
-}
-
-/// A token representing an identifier.
-class IdentifierToken implements Token {
-  final type = TokenType.identifier;
-  final FileSpan span;
-
-  /// The name of the identifier.
-  final String name;
-
-  IdentifierToken(this.name, this.span);
-
-  String toString() => 'identifier "$name"';
-}
-
-/// An enumeration of types of tokens.
-class TokenType {
-  /// A `(` character.
-  static const leftParen = const TokenType._("left paren");
-
-  /// A `)` character.
-  static const rightParen = const TokenType._("right paren");
-
-  /// A `||` sequence.
-  static const or = const TokenType._("or");
-
-  /// A `&&` sequence.
-  static const and = const TokenType._("and");
-
-  /// A `!` character.
-  static const not = const TokenType._("not");
-
-  /// A `?` character.
-  static const questionMark = const TokenType._("question mark");
-
-  /// A `:` character.
-  static const colon = const TokenType._("colon");
-
-  /// A named identifier.
-  static const identifier = const TokenType._("identifier");
-
-  /// The end of the selector.
-  static const endOfFile = const TokenType._("end of file");
-
-  /// The name of the token type.
-  final String name;
-
-  const TokenType._(this.name);
-
-  String toString() => name;
-}