Remove dart2dart support from testing scripts and status files

tools/testing/dart/co19_test_config.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.
 
 library co19_test_config;
 
 import 'path.dart';
 import 'test_suite.dart';
 
 class Co19TestSuite extends StandardTestSuite {
   RegExp _testRegExp = new RegExp(r"t[0-9]{2}.dart$");
 
   Co19TestSuite(Map configuration)
       : super(configuration,
               "co19",
               new Path("tests/co19/src"),
               ["tests/co19/co19-co19.status",
                "tests/co19/co19-analyzer.status",
                "tests/co19/co19-analyzer2.status",
                "tests/co19/co19-runtime.status",
-               "tests/co19/co19-dart2dart.status",
                "tests/co19/co19-dart2js.status",
                "tests/co19/co19-dartium.status"]);
 
   bool isTestFile(String filename) => _testRegExp.hasMatch(filename);
   bool get listRecursively => true;
 }