Move Tokenfactory, AstFactory and ElementFactory from tests to the testing/ Folder.

pkg/analyzer/lib/src/generated/testing/token_factory.dart

+// Copyright (c) 2014, 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.
+
+// This code was auto-generated, is not intended to be edited, and is subject to
+// significant change. Please see the README file for more information.
+
+library engine.testing.token_factory;
+
+import 'package:analyzer/src/generated/scanner.dart';
+
+/**
+ * The class `TokenFactory` defines utility methods that can be used to create tokens.
+ */
+class TokenFactory {
+  static Token tokenFromKeyword(Keyword keyword) => new KeywordToken(keyword, 0);
+
+  static Token tokenFromString(String lexeme) => new StringToken(TokenType.STRING, lexeme, 0);
+
+  static Token tokenFromType(TokenType type) => new Token(type, 0);
+
+  static Token tokenFromTypeAndString(TokenType type, String lexeme) => new StringToken(type, lexeme, 0);
+}