Add SdkPatcher and implement top-level function / getter / setter patching.

pkg/analyzer/test/src/dart/sdk/test_all.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.dart.sdk.test_all;
 
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
+import 'patch_test.dart' as patch_test;
 import 'sdk_test.dart' as sdk;
 
 /// Utility for manually running all tests.
 main() {
   defineReflectiveSuite(() {
+    patch_test.main();
     sdk.main();
   }, name: 'sdk');
 }