Clean up warnings and hints

pkg/analyzer/test/source/analysis_options_provider_test.dart

 // Copyright (c) 2015, 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.source.analysis_options_provider_test;
 
-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:analyzer/source/analysis_options_provider.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'package:unittest/unittest.dart';
 import 'package:yaml/yaml.dart';
 
 import '../resource_utils.dart';
@@ skipping 198 matching lines @@
         expect(ignore[1], 'sdk_ext/**');
       }
     }
   }
 
   Map<String, YamlNode> _getOptions(String posixPath, {bool crawlUp: false}) {
     Resource resource = pathTranslator.getResource(posixPath);
     return provider.getOptions(resource, crawlUp: crawlUp);
   }
 }