Use Element's source paths instead of URIs as a key in the index.

pkg/analysis_server/lib/src/services/search/hierarchy.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 services.hierarchy;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analysis_server/src/services/search/element_visitors.dart';
@@ skipping 46 matching lines @@
 
 /**
  * Returns a [Set] with direct subclasses of [seed].
  */
 Future<Set<ClassElement>> getDirectSubClasses(SearchEngine searchEngine,
     ClassElement seed) {
   return searchEngine.searchSubtypes(seed).then((List<SearchMatch> matches) {
     Set<ClassElement> subClasses = new HashSet<ClassElement>();
     for (SearchMatch match in matches) {
       ClassElement subClass = match.element;
-      if (subClass.context == seed.context) {
-        subClasses.add(subClass);
-      }
+      subClasses.add(subClass);
     }
     return subClasses;
   });
 }
 
 
 /**
  * @return all implementations of the given {@link ClassMemberElement} is its superclasses and
  *         their subclasses.
  */
@@ skipping 122 matching lines @@
  * its variable, otherwise returns [element].
  */
 Element getSyntheticAccessorVariable(Element element) {
   if (element is PropertyAccessorElement) {
     if (element.isSynthetic) {
       return element.variable;
     }
   }
   return element;
 }