[Kernel] Replace --use-dfe with --no-dfe

tools/testing/dart/test_options.dart

 // Copyright (c) 2013, 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 test_options_parser;
 
 import "dart:io";
 import "drt_updater.dart";
 import "test_suite.dart";
 import "path.dart";
@@ skipping 283 matching lines @@
       new _TestOptionSpecification(
           'verbose', 'Verbose output', ['-v', '--verbose'], [], false,
           type: 'bool'),
       new _TestOptionSpecification(
           'verify-ir', 'Verify kernel IR', ['--verify-ir'], [], false,
           type: 'bool'),
       new _TestOptionSpecification(
           'no-tree-shake', 'Disable kernel IR tree shaking', ['--no-tree-shake'], [], false,
           type: 'bool'),
       new _TestOptionSpecification(
-          'useDFE', 'Use Kernel Isolate', ['--use-dfe'], [], true,
+          'noDFE', 'Do not use Kernel Isolate', ['--no-dfe'], [], false,
           type: 'bool'),
       new _TestOptionSpecification(
           'useFasta', 'Use Fasta in Kernel Isolate', ['--use-fasta'], [], false,
           type: 'bool'),
       new _TestOptionSpecification(
           'list', 'List tests only, do not run them', ['--list'], [], false,
           type: 'bool'),
       new _TestOptionSpecification(
           'report_in_json',
           'When doing list, output result summary in json only.',
@@ skipping 691 matching lines @@
         return option;
       }
     }
     print('Unknown test option $name');
     exit(1);
     return null; // Unreachable.
   }
 
   List<_TestOptionSpecification> _options;
 }