Implement continue for switch.

tests/language/switch_label2_test.dart

+// Copyright (c) 2011, 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.
+
+// Test switch statement using labels.
+
+import 'package:expect/expect.dart';
+
+void main() {
+  doSwitch(0, [0, 2]);
+  doSwitch(1, [1]);
+  doSwitch(2, [2]);
+  doSwitch(3, [3, 1]);
+}
+
+void doSwitch(int target, List expect) {
+  List list = [];
+  switch (target) {
+  case 0:
+    list.add(0);
+    continue case2;
+  case1: case 1:
+    list.add(1);
+    break;
+  case2: case 2:
+    list.add(2);
+    break;
+  case 3:
+    list.add(3);
+    continue case1;
+  }
+  Expect.listEquals(expect, list);
+}