Extend Future.then inference to subclasses

pkg/analyzer/test/src/summary/resynthesize_ast_test.dart

 // Copyright (c) 2016, 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 analyzer.test.src.summary.resynthesize_ast_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/generated/engine.dart'
@@ skipping 191 matching lines @@
   }
 
   @override
   @failingTest
   void test_constructors_inferFromArguments_redirectingFactory() {
     super.test_constructors_inferFromArguments_redirectingFactory();
   }
 
   @override
   @failingTest
+  void test_futureThen() {
+    super.test_futureThen();
+  }
+
+  @override
+  @failingTest
+  void test_futureThen_conditional() {
+    super.test_futureThen_conditional();
+  }
+
+  @override
+  @failingTest
+  void test_futureThen_upwards() {
+    super.test_futureThen_upwards();
+  }
+
+  @override
+  @failingTest
+  void test_futureUnion_asyncConditional() {
+    super.test_futureUnion_asyncConditional();
+  }
+
+  @override
+  @failingTest
+  void test_futureUnion_downwards() {
+    super.test_futureUnion_downwards();
+  }
+
+  @override
+  @failingTest
   void test_genericMethods_inferJSBuiltin() {
     super.test_genericMethods_inferJSBuiltin();
   }
 
   void test_infer_extractIndex_custom() {
     var unit = checkFile('''
 class A {
   String operator [](_) => null;
 }
 var a = new A();
@@ skipping 629 matching lines @@
  * directly, because then it would be overriding a field at the site where the
  * mixin is instantiated.
  */
 abstract class _AstResynthesizeTestMixinInterface {
   /**
    * A test should return `true` to indicate that a missing file at the time of
    * summary resynthesis shouldn't trigger an error.
    */
   bool get allowMissingFiles;
 }