kernel->ssa: implement assert statements

tests/compiler/dart2js/kernel/assert_test.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.
+
+import 'package:compiler/src/commandline_options.dart' show Flags;
+import 'package:test/test.dart';
+
+import 'helper.dart' show check;
+
+main() {
+  test('assert without message', () {
+    String code = '''
+bool foo() => 2 + 2 == 4;
+main() {
+  assert(foo());
+}''';
+    return check(code, extraOptions: const <String>[Flags.enableCheckedMode]);
+  });
+
+  test('assert with message', () {
+    String code = '''
+bool foo() => 2 + 2 == 4;
+main() {
+  assert(foo(), "foo failed");
+}''';
+    return check(code,
+        // disable type inference because kernel doesn't yet support
+        // checked mode type checks
+        disableTypeInference: false,
+        extraOptions: const <String>[
+          Flags.enableCheckedMode,
+          Flags.enableAssertMessage,
+        ]);
+  });
+}