Implement search for direct subtypes and enable `search.getTypeHierarchy` request.

pkg/analysis_server/lib/src/search/search_domain.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 search.domain;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
@@ skipping 123 matching lines @@
     List<SearchMatch> matches =
         await searchEngine.searchTopLevelDeclarations(params.pattern);
     matches = SearchMatch.withNotNullElement(matches);
     _sendSearchNotification(searchId, true, matches.map(toResult));
   }
 
   /**
    * Implement the `search.getTypeHierarchy` request.
    */
   Future getTypeHierarchy(protocol.Request request) async {
-    if (server.options.enableNewAnalysisDriver) {
-      // TODO(scheglov) implement for the new analysis driver
-      protocol.Response response =
-          new protocol.SearchGetTypeHierarchyResult(hierarchyItems: [])
-              .toResponse(request.id);
-      server.sendResponse(response);
-      return;
-    }
     var params = new protocol.SearchGetTypeHierarchyParams.fromRequest(request);
     String file = params.file;
     // wait for analysis
-    if (params.superOnly == true) {
-      await server.onFileAnalysisComplete(file);
-    } else {
-      await server.onAnalysisComplete;
+    if (!server.options.enableNewAnalysisDriver) {
+      if (params.superOnly == true) {
+        await server.onFileAnalysisComplete(file);
+      } else {
+        await server.onAnalysisComplete;
+      }
     }
     // prepare element
     Element element = await server.getElementAtOffset(file, params.offset);
     if (element == null) {
       _sendTypeHierarchyNull(request);
       return;
     }
     // maybe supertype hierarchy only
     if (params.superOnly == true) {
       TypeHierarchyComputer computer =
@@ skipping 62 matching lines @@
   void _sendTypeHierarchyNull(protocol.Request request) {
     protocol.Response response =
         new protocol.SearchGetTypeHierarchyResult().toResponse(request.id);
     server.sendResponse(response);
   }
 
   static protocol.SearchResult toResult(SearchMatch match) {
     return protocol.newSearchResult_fromMatch(match);
   }
 }