Fix some analysis issues.

pkg/analysis_server/test/services/completion/dart/completion_manager_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.completion.dart.manager;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
 import 'package:analysis_server/src/services/completion/completion_core.dart';
@@ skipping 24 matching lines @@
     addSource(
         '/libA.dart',
         '''
 library libA;
 /// My class.
 /// Short description.
 ///
 /// Longer description.
 class A {}
 ''');
-    var libSource = addSource(
+    addSource(
         '/libB.dart',
         '''
 library libB;
 import "/libA.dart" as foo;
 part '$testFile';
 ''');
     addTestSource('part of libB; main() {^}');
 
     // Build the request
     CompletionRequestImpl baseRequest = new CompletionRequestImpl(
@@ skipping 27 matching lines @@
     void assertImportedLib(String expectedUri) {
       ImportElement importElem = importNamed(expectedUri);
       expect(importElem.importedLibrary.exportNamespace, isNotNull);
     }
 
     // Assert that the new imports each have an export namespace
     assertImportedLib(null /* dart:core */);
     assertImportedLib('/libA.dart');
   }
 }