Re-enable kernel unit tests on platforms where they are supported.

pkg/kernel/test/type_substitution_identity_test_disabled.dart

Index: pkg/kernel/test/type_substitution_identity_test_disabled.dart
diff --git a/pkg/kernel/test/type_substitution_identity_test_disabled.dart b/pkg/kernel/test/type_substitution_identity_test_disabled.dart
deleted file mode 100644
index 2e6c263c8ab0fab4a9924f7e7549d87a87f6d5c8..0000000000000000000000000000000000000000
--- a/pkg/kernel/test/type_substitution_identity_test_disabled.dart
+++ /dev/null
@@ -1,30 +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 'package:kernel/kernel.dart';
-import 'package:kernel/type_algebra.dart';
-import 'type_parser.dart';
-import 'type_unification_test_disabled.dart' show testCases;
-import 'package:test/test.dart';
-
-checkType(DartType type) {
-  var map = {new TypeParameter(): const DynamicType()};
-  var other = substitute(type, map);
-  if (!identical(type, other)) {
-    fail('Identity substitution test failed for $type');
-  }
-  other = Substitution.fromUpperAndLowerBounds(map, map).substituteType(type);
-  if (!identical(type, other)) {
-    fail('Identity bounded substitution test failed for $type');
-  }
-}
-
-main() {
-  for (var testCase in testCases) {
-    test('$testCase', () {
-      var env = new LazyTypeEnvironment();
-      checkType(env.parse(testCase.type1));
-      checkType(env.parse(testCase.type2));
-    });
-  }
-}