Add OCCURRENCES_CONTRIBUTOR_EXTENSION_POINT_ID.

pkg/analysis_server/lib/src/domains/analysis/navigation.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 domains.analysis.navigation;
 
 import 'dart:collection';
 
-import 'package:analysis_server/analysis/navigation/navigation_core.dart';
+import 'package:analysis_server/analysis/navigation_core.dart';
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/collections.dart';
 import 'package:analysis_server/src/protocol_server.dart' as protocol;
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, AnalysisEngine;
 import 'package:analyzer/src/generated/java_engine.dart' show CaughtException;
 import 'package:analyzer/src/generated/source.dart' show Source;
 
 /**
  * Compute all known navigation information for the given part of [source].
@@ skipping 77 matching lines @@
           location.offset,
           location.length,
           location.startLine,
           location.startColumn);
       targets.add(target);
       targetMap[pair] = index;
     }
     return index;
   }
 }