Reland "Merge more Kernel infrastructure from kernel_sdk SDK fork."

tests/kernel/unsorted/nullable_operator_test.dart

Index: tests/kernel/unsorted/nullable_operator_test.dart
diff --git a/pkg/dev_compiler/test/codegen/language/variable_named_dart_test.dart b/tests/kernel/unsorted/nullable_operator_test.dart
similarity index 63%
copy from pkg/dev_compiler/test/codegen/language/variable_named_dart_test.dart
copy to tests/kernel/unsorted/nullable_operator_test.dart
index 233b60f899e88253c5ca472b24fd67481e550624..2643a83c9b8e4c457c1f8c403f4191994818f84e 100644
--- a/pkg/dev_compiler/test/codegen/language/variable_named_dart_test.dart
+++ b/tests/kernel/unsorted/nullable_operator_test.dart
@@ -2,9 +2,12 @@
 // 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.
 
-import 'package:expect/expect.dart';
+import 'expect.dart';
+
+mkOne() => 1;
+mkNull() => null;
 
 main() {
-  dynamic dart = 123;
-  Expect.equals(dart.toDouble(), 123.0);
+  Expect.isTrue((mkOne() ?? 2) == 1);
+  Expect.isTrue((mkNull() ?? 2) == 2);
 }