More steps toward making server strong mode clean

pkg/analysis_server/lib/src/search/element_references.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.element_references;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/collections.dart';
 import 'package:analysis_server/src/protocol_server.dart'
@@ skipping 46 matching lines @@
       }
       // do search
       futureGroup.add(_findSingleElementReferences(refElement));
     }
     return futureGroup.future;
   }
 
   /**
    * Returns a [Future] completing with a [List] of references to [element].
    */
-  Future<List<SearchResult>> _findSingleElementReferences(Element element) {
-    Future<List<SearchMatch>> matchesFuture =
-        searchEngine.searchReferences(element);
-    return matchesFuture.then((List<SearchMatch> matches) {
-      return matches.map(toResult).toList();
-    });
+  Future<List<SearchResult>> _findSingleElementReferences(
+      Element element) async {
+    List<SearchMatch> matches = await searchEngine.searchReferences(element);
+    return matches.map(toResult).toList();
   }
 
   /**
    * Returns a [Future] completing with [Element]s to search references to.
    *
    * If a [ClassMemberElement] is given, each corresponding [Element] in the
    * hierarchy is returned.
    *
    * Otherwise, only references to [element] should be searched.
    */
@@ skipping 64 matching lines @@
    * Adds a [Future] or an [E] value to results.
    */
   void add(value) {
     if (value is Future) {
       _futures.add(value as Future<List<E>>);
     } else {
       _futures.add(new Future.value(<E>[value as E]));
     }
   }
 }