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

pkg/smoke/test/codegen/testing_resolver_utils.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.
 
 /// Utility functions to test the code generation tools with the resolver.
 // Note, this is just for simple tests, so we restricted the logic to only
 // support root-relative imports. For more sophisticated stuff, you should be
 // using the test helpers in `package:code_transformers`.
 library smoke.test.codegen.testing_resolver_utils;
 
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/sdk_io.dart' show DirectoryBasedDartSdk;
-import 'package:code_transformers/src/dart_sdk.dart' show
-    testingDartSdkDirectory;
+import 'package:code_transformers/tests.dart' show testingDartSdkDirectory;
 
 class LibraryProvider {
   final AnalysisContext _analyzer;
   final Map<String, Source> _allSources;
   LibraryProvider(this._analyzer, this._allSources);
   LibraryElement libraryFor(String uri) =>
       _analyzer.computeLibraryElement(_allSources[uri]);
 }
 
 LibraryProvider initAnalyzer(Map<String, String> contents) {
@@ skipping 61 matching lines @@
   // using the test helpers in `package:code_transformers`.
   Source resolveRelative(Uri uri) {
     if (uri.path.startsWith('/')) return allSources['${uri.path}'];
     throw new UnimplementedError('relative URIs not supported: $uri');
   }
 
   void getContentsToReceiver(Source_ContentReceiver receiver) {
     receiver.accept(rawContents, modificationStamp);
   }
 }