Check implicit super call in synthetic constructor.

tests/language/constructor11_test.dart

+// Copyright (c) 2014, 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.
+
+// Check that the implicit super call for synthetic constructors are checked.
+
+import "package:expect/expect.dart";
+
+class A {
+  final x;
+  A([this.x = 499]);
+}
+
+class B extends A {
+}
+
+// ==========
+
+class X {
+  final x;
+  X([this.x = 42]);
+}
+
+class Y extends X {
+}
+
+class Z extends Y {
+  Z() : super();
+}
+
+// ==============
+
+class F {
+  final x;
+  F([this.x = 99]);
+}
+
+class G extends F {
+}
+
+class H extends G {
+}
+
+main() {
+  Expect.equals(499, new B().x);
+  Expect.equals(42, new Z().x);
+  Expect.equals(99, new H().x);
+}