Make AnalysisSErver APIs to access unit/node/element asynchronous.

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 42 matching lines @@
       // TODO(scheglov) implement for the new analysis driver
       String searchId = (_nextSearchId++).toString();
       var result = new protocol.SearchFindElementReferencesResult();
       result.id = searchId;
       _sendSearchResult(request, result);
       _sendSearchNotification(searchId, true, <protocol.SearchResult>[]);
       return;
     }
     var params =
         new protocol.SearchFindElementReferencesParams.fromRequest(request);
+    String file = params.file;
     await server.onAnalysisComplete;
     // prepare element
-    Element element = server.getElementAtOffset(params.file, params.offset);
+    Element element = await server.getElementAtOffset(file, params.offset);
     if (element is ImportElement) {
       element = (element as ImportElement).prefix;
     }
     if (element is FieldFormalParameterElement) {
       element = (element as FieldFormalParameterElement).field;
     }
     if (element is PropertyAccessorElement) {
       element = (element as PropertyAccessorElement).variable;
     }
     // respond
@@ skipping 79 matching lines @@
     }
     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;
     }
     // prepare element
-    Element element = server.getElementAtOffset(file, params.offset);
+    Element element = await server.getElementAtOffset(file, params.offset);
     if (element == null) {
       _sendTypeHierarchyNull(request);
       return;
     }
     // maybe supertype hierarchy only
     if (params.superOnly == true) {
       TypeHierarchyComputer computer =
           new TypeHierarchyComputer(searchEngine, element);
       List<protocol.TypeHierarchyItem> items = computer.computeSuper();
       protocol.Response response =
@@ skipping 59 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);
   }
 }