Clean up warnings and hints

pkg/analyzer/lib/source/embedder.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.
 
 @deprecated
 library analyzer.source.embedder;
 
 import 'dart:collection' show HashMap;
-import 'dart:core' hide Resource;
+import 'dart:core';
 import 'dart:io' as io;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/source/package_map_provider.dart'
     show PackageMapProvider;
 import 'package:analyzer/src/generated/java_io.dart' show JavaFile;
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/sdk_io.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart' show FileBasedSource;
@@ skipping 156 matching lines @@
   @override
   Uri restoreAbsolute(Source source) {
     String path = source.fullName;
     if (path.length > 3 && path[1] == ':' && path[2] == '\\') {
       path = '/${path[0]}:${path.substring(2).replaceAll('\\', '/')}';
     }
     Source sdkSource = dartSdk.fromFileUri(Uri.parse('file://$path'));
     return sdkSource?.uri;
   }
 }