Revert "Adding package:code_transformers for unifying common transformers code"

pkg/code_transformers/lib/src/dart_sdk.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.
-
-library code_transformers.src.dart_sdk;
-
-import 'dart:convert' as convert;
-import 'dart:io' show Directory, Platform, Process;
-import 'package:path/path.dart' as path;
-
-
-/// Attempts to provide the current Dart SDK directory.
-///
-/// Note that this may not be correct when executing outside of `pub`.
-String get dartSdkDirectory {
-  if (path.split(Platform.executable).length == 1) {
-    // TODO(blois): make this cross-platform.
-    // HACK: A single part, hope it's on the path.
-    var result = Process.runSync('which', ['dart'],
-        stdoutEncoding: convert.UTF8);
-    return path.dirname(path.dirname(result.stdout));
-  }
-  var sdkDir = path.dirname(path.absolute(Platform.executable));
-  // If there's a sub-dir named dart-sdk then we're most likely executing from
-  // a dart enlistment build directory.
-  if (new Directory(path.join(sdkDir, 'dart-sdk')).existsSync()) {
-    return path.join(sdkDir, 'dart-sdk');
-  }
-  return sdkDir;
-}