Fixes how to lookup sdk dir to support tests deeper inside test/ folders.

pkg/code_transformers/lib/src/dart_sdk.dart

Index: pkg/code_transformers/lib/src/dart_sdk.dart
diff --git a/pkg/code_transformers/lib/src/dart_sdk.dart b/pkg/code_transformers/lib/src/dart_sdk.dart
index d31169a8fd8f851539ce4fab7a863d1209d26255..7b6f8e694c821af6bc6dd2802f3235bda9032c48 100644
--- a/pkg/code_transformers/lib/src/dart_sdk.dart
+++ b/pkg/code_transformers/lib/src/dart_sdk.dart
@@ -5,7 +5,7 @@
 library code_transformers.src.dart_sdk;
 
 import 'dart:convert' as convert;
-import 'dart:io' show Directory, File, Platform, Process;
+import 'dart:io' show File, Platform, Process;
 import 'package:path/path.dart' as path;
 
 
@@ -47,16 +47,3 @@ String get dartSdkDirectory {
 
   return null;
 }
-
-/// Variant of [dartSdkDirectory] which includes additional cases only
-/// typically encountered in Dart's testing environment.
-String get testingDartSdkDirectory {
-  var sdkDir = dartSdkDirectory;
-  if (sdkDir == null) {
-    // If we cannot find the SDK dir, then assume this is being run from Dart's
-    // source directory and this script is the main script.
-    sdkDir = path.join(
-        path.dirname(path.fromUri(Platform.script)), '..', '..', '..', 'sdk');
-  }
-  return sdkDir;
-}