Move dartk to the tool folder

pkg/kernel/test/batch_consistency.dart

 // Copyright (c) 2016, 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 kernel.batch_consistency;
 
 import 'dart:async';
 import 'dart:io';
-import '../bin/dartk.dart' as dartk;
+import '../tool/dartk.dart' as dartk;
 import '../bin/batch_util.dart';
 import 'package:path/path.dart' as pathlib;
 import 'package:test/test.dart';
 
 String usage = """
 Usage: batch_consistency [options] -- files...
 
 Run dartk on the given files, both separately and in a batch, and check that
 the output is identical for the two modes.
 """;
@@ skipping 58 matching lines @@
       }
       if (results[0] == CompilerOutcome.Fail) {
         failed = true;
       }
       if (!failed && !await areFilesEqual(outputFiles[0], outputFiles[1])) {
         fail('Batch mode output differs for $file');
       }
     });
   }
 }