Tweak navigation for 'part of' directives.

pkg/analysis_server/test/analysis/notification_navigation_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.analysis.notification.navigation;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
@@ skipping 646 matching lines @@
       assertHasOperatorRegion('] += 2;', 1, '[]=(index,', 3);
       assertHasOperatorRegion('+= 2;', 2, '+(other)', 1);
     });
   }
 
   test_partOf() {
     var libCode = 'library lib; part "test.dart";';
     var libFile = addFile('$projectPath/bin/lib.dart', libCode);
     addTestFile('part of lib;');
     return prepareNavigation().then((_) {
-      assertHasRegionString('part of lib');
+      assertHasRegionString('lib');
       assertHasFileTarget(libFile, libCode.indexOf('lib;'), 'lib'.length);
     });
   }
 
   test_string_export() {
     var libCode = 'library lib;';
     var libFile = addFile('$projectPath/bin/lib.dart', libCode);
     addTestFile('export "lib.dart";');
     return prepareNavigation().then((_) {
       assertHasRegionString('"lib.dart"');
@@ skipping 121 matching lines @@
   test_type_void() {
     addTestFile('''
 void main() {
 }
 ''');
     return prepareNavigation().then((_) {
       assertNoRegionAt('void');
     });
   }
 }