null namespace check - fixes #25331

pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart

 // Copyright (c) 2015, 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 services.completion.dart.manager;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/provisional/completion/completion_core.dart'
@@ skipping 186 matching lines @@
     if (_opType == null) {
       _opType = new OpType.forCompletion(target, offset);
     }
     return _opType;
   }
 
   // For internal use only
   @override
   Future<List<Directive>> resolveDirectives() async {
     CompilationUnit libUnit;
-    if (librarySource == source) {
-      libUnit = target.unit;
-    } else if (librarySource != null) {
+    if (librarySource != null) {
       // TODO(danrubel) only resolve the directives
       const RESOLVE_DIRECTIVES_TAG = 'resolve directives';
       performance.logStartTime(RESOLVE_DIRECTIVES_TAG);
       libUnit = await new AnalysisFutureHelper<CompilationUnit>(
               context,
               new LibrarySpecificUnit(librarySource, librarySource),
               RESOLVED_UNIT3)
           .computeAsync();
       performance.logElapseTime(RESOLVE_DIRECTIVES_TAG);
     }
@@ skipping 180 matching lines @@
               // Replacement range for import URI
               return new ReplacementRange(start, end - start);
             }
           }
         }
       }
     }
     return new ReplacementRange(requestOffset, 0);
   }
 }