Clean up warnings and hints

pkg/analyzer/lib/source/pub_package_map_provider.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.source.pub_package_map_provider;
 
 import 'dart:collection';
 import 'dart:convert';
-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';
 import 'package:analyzer/src/dart/sdk/sdk.dart';
 import 'package:analyzer/src/generated/engine.dart';
 
 /**
  * The function used to run pub list.
  */
@@ skipping 155 matching lines @@
     String workingDirectory = folder.path;
     int subprocessId = AnalysisEngine.instance.instrumentationService
         .logSubprocessStart(executablePath, arguments, workingDirectory);
     io.ProcessResult result = io.Process
         .runSync(executablePath, arguments, workingDirectory: workingDirectory);
     AnalysisEngine.instance.instrumentationService.logSubprocessResult(
         subprocessId, result.exitCode, result.stdout, result.stderr);
     return result;
   }
 }