Revert "Remove unnecessary hide clauses"

pkg/analyzer/lib/source/analysis_options_provider.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.source.analysis_options_provider;
 
-import 'dart:core';
+import 'dart:core' hide Resource;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/util/yaml.dart';
 import 'package:source_span/source_span.dart';
 import 'package:yaml/yaml.dart';
 
 /// Provide the options found in the analysis options file.
 class AnalysisOptionsProvider {
   /// Provide the options found in either
@@ skipping 33 matching lines @@
 
     YamlNode safelyLoadYamlNode() {
       try {
         return loadYamlNode(optionsSource);
       } on YamlException catch (e) {
         throw new OptionsFormatException(e.message, e.span);
       } catch (e) {
         throw new OptionsFormatException('Unable to parse YAML document.');
       }
     }
-
     YamlNode doc = safelyLoadYamlNode();
 
     // Empty options.
     if (doc is YamlScalar && doc.value == null) {
       return options;
     }
     if ((doc != null) && (doc is! YamlMap)) {
       throw new OptionsFormatException(
           'Bad options file format (expected map, got ${doc.runtimeType})',
           doc.span);
@@ skipping 53 matching lines @@
 /// Thrown on options format exceptions.
 class OptionsFormatException implements Exception {
   final String message;
   final SourceSpan span;
   OptionsFormatException(this.message, [this.span]);
 
   @override
   String toString() =>
       'OptionsFormatException: ${message?.toString()}, ${span?.toString()}';
 }