fix #27040, promote the upper bound of a type parameter

pkg/analyzer/test/src/task/strong/checker_test.dart

 // Copyright (c) 2015, 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.task.strong.checker_test;
 
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'strong_test_helper.dart';
 
@@ skipping 3681 matching lines @@
   Object x;
   if (x is int) {
     int y = x;
     String z = /*error:INVALID_ASSIGNMENT*/x;
   }
 }
 ''');
   }
 
   void test_typePromotionFromTypeParameter() {
-    // Regression test for https://github.com/dart-lang/sdk/issues/26965
+    // Regression test for:
+    // https://github.com/dart-lang/sdk/issues/26965
+    // https://github.com/dart-lang/sdk/issues/27040
     checkFile(r'''
 void f/*<T>*/(/*=T*/ object) {
   if (object is String) print(object.substring(1));
 }
 void g/*<T extends num>*/(/*=T*/ object) {
   if (object is int) print(object.isEven);
   if (object is String) print(/*info:DYNAMIC_INVOKE*/object.substring(1));
 }
 class Clonable<T> {}
 class SubClonable<T> extends Clonable<T> {
   T m(T t) => t;
 }
 void h/*<T extends Clonable<T>>*/(/*=T*/ object) {

[Leaf, 2016/09/30 05:00:04]

Test that object is usable as a SubClonable<T> as well as a T?

[Jennifer Messerly, 2016/09/30 16:58:03]

I think `object.m` is supposed to illustrate that. Perhaps would be better not
all on the same line though and with comments.

[Leaf, 2016/09/30 17:00:30]

Sort of.  object.m tests that SubClonable methods can be called on it.  Just to
be paranoid I thought it might be useful to check that assignability actually
works as well, since that follows different code paths

   if (/*info:NON_GROUND_TYPE_CHECK_INFO*/object is SubClonable/*<T>*/) {
-    // Note we need to cast back to T, because promotion lost that type info.
-    print(object.m(object as dynamic/*=T*/));
+    print(object.m(object));
   }
 }
 ''');
   }
 
   void test_typeSubtyping_assigningClass() {
     checkFile('''
 class A {}
 class B extends A {}
 
@@ skipping 220 matching lines @@
 void _addMetaLibrary() {
   addFile(r'''
 library meta;
 class _Checked { const _Checked(); }
 const Object checked = const _Checked();
 
 class _Virtual { const _Virtual(); }
 const Object virtual = const _Virtual();
     ''', name: '/meta.dart');
 }