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

tests/kernel/unsorted/let_test.dart

Index: tests/kernel/unsorted/let_test.dart
diff --git a/tests/kernel/unsorted/let_test.dart b/tests/kernel/unsorted/let_test.dart
deleted file mode 100644
index 249ec491558b4a1d5eb4999498c45f5dbba2b6ab..0000000000000000000000000000000000000000
--- a/tests/kernel/unsorted/let_test.dart
+++ /dev/null
@@ -1,10 +0,0 @@
-// 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.
-
-import 'expect.dart';
-
-main() {
-  var a = [1];
-  Expect.isTrue((a..add(42))[1] == 42);
-}