Clean up warnings and hints

pkg/analyzer/test/embedder_tests.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.
 
 library analyzer.test.embedder_tests;
 
-import 'dart:core' hide Resource;
+import 'dart:core';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:path/path.dart' as path;
 
 import 'resource_utils.dart';
 import 'utils.dart';
 
 abstract class EmbedderRelatedTest {
   final String emptyPath = '/home/.pub-cache/empty';
@@ skipping 31 matching lines @@
   void setUp() {
     initializeTestEnvironment(path.context);
     buildResourceProvider();
   }
 
   void tearDown() {
     initializeTestEnvironment();
     clearResourceProvider();
   }
 }