Rewrite package:fasta/testing URIs.

pkg/front_end/test/fasta/outline_test.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.md file.
 
 library fasta.test.outline_test;
 
 import 'dart:async' show
     Future;
 
-import 'package:fasta/testing/suite.dart';
+import 'package:front_end/src/fasta/testing/suite.dart';
 
 Future<FeContext> createContext(
     Chain suite, Map<String, String> environment) {
   return TestContext.create(suite, environment, FeContext.create);
 }
 
 main(List<String> arguments) => runMe(arguments, createContext);