include unimported sdk lib types as low priority suggestions

pkg/analysis_server/test/mock_sdk.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 testing.mock_sdk;
 
 import 'package:analyzer/file_system/file_system.dart' as resource;
 import 'package:analyzer/file_system/memory_file_system.dart' as resource;
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/sdk.dart';
@@ skipping 89 matching lines @@
 void print(Object object) {}
 ''');
 
   static const _MockSdkLibrary LIB_ASYNC = const _MockSdkLibrary('dart:async',
       '/lib/async/async.dart', '''
 library dart.async;
 
 import 'dart:math';
 
 class Future<T> {
+  factory Future(computation()) => null;
   factory Future.delayed(Duration duration, [T computation()]) => null;
   factory Future.value([value]) => null;
   static Future wait(List<Future> futures) => null;
 }
 
 class Stream<T> {}
 abstract class StreamTransformer<S, T> {}
 ''');
 
   static const _MockSdkLibrary LIB_COLLECTION = const _MockSdkLibrary(
@@ skipping 181 matching lines @@
   bool get isInternal => throw unimplemented;
 
   @override
   bool get isShared => throw unimplemented;
 
   @override
   bool get isVmLibrary => throw unimplemented;
 
   UnimplementedError get unimplemented => new UnimplementedError();
 }