Use single unit/node/element.

pkg/analysis_server/lib/src/operation/operation_analysis.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 operation.analysis;
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/computer/computer_highlights.dart';
 import 'package:analysis_server/src/computer/computer_highlights2.dart';
 import 'package:analysis_server/src/computer/computer_outline.dart';
@@ skipping 17 matching lines @@
  */
 runWithActiveContext(AnalysisContext context, f()) {
   if (context is InternalAnalysisContext && !context.isActive) {
     context.isActive = true;
     try {
       return f();
     } finally {
       context.isActive = false;
     }
   } else {
-    f();
+    return f();
   }
 }
 
 scheduleImplementedNotification(
     AnalysisServer server, Iterable<String> files) async {
   SearchEngine searchEngine = server.searchEngine;
   if (searchEngine == null) {
     return;
   }
   for (String file in files) {
@@ skipping 487 matching lines @@
 abstract class _SingleFileOperation extends SourceSensitiveOperation {
   final String file;
 
   _SingleFileOperation(AnalysisContext context, this.file) : super(context);
 
   @override
   bool shouldBeDiscardedOnSourceChange(Source source) {
     return source.fullName == file;
   }
 }