Restructure the public API for server

pkg/analysis_server/lib/src/domains/analysis/occurrences.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 domains.analysis.occurrences;
 
-import 'package:analysis_server/analysis/occurrences_core.dart';
+import 'package:analysis_server/plugin/analysis/occurrences/occurrences_core.dart';
 import 'package:analysis_server/src/analysis_server.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 occurrences for the given [source].
  */
@@ skipping 33 matching lines @@
       List<int> offsets = _merge(existing.offsets, current.offsets);
       current = new protocol.Occurrences(element, offsets, existing.length);
     }
     elementOccurrences[element] = current;
   }
 
   static List<int> _merge(List<int> a, List<int> b) {
     return <int>[]..addAll(a)..addAll(b);
   }
 }