Fix 'Unused local variable' hints in analyzer and analysis_server.

pkg/analysis_server/test/services/refactoring/move_file_test.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 test.services.refactoring.move_files;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/refactoring/refactoring.dart';
@@ skipping 87 matching lines @@
       assertFileChangeResult(pathA, '''
 import '22/new_name.dart';
 ''');
       assertNoFileChange(testFile);
     });
   }
 
   test_importedLibrary_package() {
     // configure packages
     testFile = '/packages/my_pkg/aaa/test.dart';
-    File testFileRes = provider.newFile(testFile, '');
+    provider.newFile(testFile, '');
     Map<String, List<Folder>> packageMap = {
       'my_pkg': [provider.getResource('/packages/my_pkg')]
     };
     context.sourceFactory = new SourceFactory(
         [
             AbstractContextTest.SDK_RESOLVER,
             resourceResolver,
             new PackageMapUriResolver(provider, packageMap)]);
     // do testing
     String pathA = '/project/bin/a.dart';
@@ skipping 100 matching lines @@
         break;
       }
       for (ChangeNotice notice in result.changeNotices) {
         if (notice.source.fullName.startsWith('/project/')) {
           index.indexUnit(context, notice.compilationUnit);
         }
       }
     }
   }
 }