Remove unnecessary hide clauses

pkg/analyzer/lib/src/context/builder.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.src.context.context_builder;
 
 import 'dart:collection';
-import 'dart:core' hide Resource;
+import 'dart:core';
 
 import 'package:analyzer/context/declared_variables.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/plugin/options.dart';
 import 'package:analyzer/plugin/resolver_provider.dart';
 import 'package:analyzer/source/analysis_options_provider.dart';
 import 'package:analyzer/source/package_map_resolver.dart';
 import 'package:analyzer/src/dart/sdk/sdk.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/sdk.dart';
@@ skipping 550 matching lines @@
   String _readEmbedderYaml(Folder libDir) {
     File file = libDir.getChild(EMBEDDER_FILE_NAME);
     try {
       return file.readAsStringSync();
     } on FileSystemException {
       // File can't be read.
       return null;
     }
   }
 }