Remove unnecessary hide clauses

pkg/analyzer/lib/file_system/physical_file_system.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.
 
 library analyzer.file_system.physical_file_system;
 
 import 'dart:async';
-import 'dart:core' hide Resource;
+import 'dart:core';
 import 'dart:io' as io;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:analyzer/src/source/source_resource.dart';
 import 'package:analyzer/src/util/absolute_path.dart';
 import 'package:isolate/isolate_runner.dart';
 import 'package:path/path.dart';
 import 'package:watcher/watcher.dart';
 
@@ skipping 356 matching lines @@
           timer.cancel();
         }
       });
       return completer.future;
     }
     _isSpawning = true;
     _runner = await IsolateRunner.spawn();
     return _runner;
   }
 }