Start 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 28 matching lines @@
       futureGroup.add(resultsFuture);
     }
     // merge results
     return futureGroup.future;
   }
 
   /**
    * Returns a [Future] completing with a [List] of references to [element] or
    * to the corresponding hierarchy [Element]s.
    */
-  Future<List<SearchResult>> _findElementsReferences(Element element) {
-    return _getRefElements(element).then((Iterable<Element> refElements) {
-      var futureGroup = new _ConcatFutureGroup<SearchResult>();
-      for (Element refElement in refElements) {
-        // add declaration
-        if (_isDeclarationInteresting(refElement)) {
-          SearchResult searchResult = _newDeclarationResult(refElement);
-          futureGroup.add(searchResult);
-        }
-        // do search
-        futureGroup.add(_findSingleElementReferences(refElement));
+  Future<List<SearchResult>> _findElementsReferences(Element element) async {
+    Iterable<Element> refElements = await _getRefElements(element);
+    var futureGroup = new _ConcatFutureGroup<SearchResult>();
+    for (Element refElement in refElements) {
+      // add declaration
+      if (_isDeclarationInteresting(refElement)) {
+        SearchResult searchResult = _newDeclarationResult(refElement);
+        futureGroup.add(searchResult);
       }
-      return futureGroup.future;
-    });
+      // 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();
@@ skipping 69 matching lines @@
 
   Future<List<E>> get future {
     return Future.wait(_futures).then(concatToList);
   }
 
   /**
    * Adds a [Future] or an [E] value to results.
    */
   void add(value) {
     if (value is Future) {
-      _futures.add(value);
+      _futures.add(value as Future<List<E>>);
     } else {
-      _futures.add(new Future.value(<E>[value]));
+      _futures.add(new Future.value(<E>[value as E]));
     }
   }
 }