Move dartk to the tool folder

pkg/kernel/tool/dartk.dart

 #!/usr/bin/env 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.
 
 import 'dart:async';
 import 'dart:io';
 
-import 'batch_util.dart';
-import 'util.dart';
+import '../bin/batch_util.dart';

[Siggi Cherem (dart-lang), 2017/04/24 23:20:37]

I only moved dartk to fix the package-dependency issue, but I can move all the
scripts in `bin` if that's what you prefer (for example, if they are all
intended for internal use only).

Let me know, I'd be happy to do so with this CL.

+import '../bin/util.dart';
 
 import 'package:args/args.dart';
 import 'package:analyzer/src/kernel/loader.dart';
 import 'package:kernel/application_root.dart';
 import 'package:kernel/verifier.dart';
 import 'package:kernel/kernel.dart';
 import 'package:kernel/log.dart';
 import 'package:kernel/target/targets.dart';
 import 'package:kernel/transformations/treeshaker.dart';
 import 'package:path/path.dart' as path;
@@ skipping 424 matching lines @@
     int flushTime = watch.elapsedMilliseconds - time;
     print('writer.flush_time = $flushTime ms');
   }
 
   if (options['tolerant']) {
     return CompilerOutcome.Ok;
   }
 
   return errors.length > 0 ? CompilerOutcome.Fail : CompilerOutcome.Ok;
 }