Implement super initializers.

frog/tests/leg_only/src/SuperConstructor2Test.dart

Index: frog/tests/leg_only/src/SuperConstructor2Test.dart
diff --git a/frog/tests/leg_only/src/SuperConstructor2Test.dart b/frog/tests/leg_only/src/SuperConstructor2Test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..4c5f30261bbb01fed247228ad8f432654ad35cda
--- /dev/null
+++ b/frog/tests/leg_only/src/SuperConstructor2Test.dart
@@ -0,0 +1,21 @@
+// 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.
+
+class A {
+  int x;
+  A() : x = 27;
+}
+
+class B extends A {
+  B();
+}
+
+class C extends A {}
+
+main() {
+  A a = new B();
+  Expect.equals(27, a.x);
+  a = new C();
+  Expect.equals(27, a.x);
+}