Implement implicit constructors in mixin applications.

tests/language/mixin_super_constructor_test.dart

+// Copyright (c) 2013, 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:expect/expect.dart";
+
+class Base {
+  int i, j;
+  Base.ctor(int i, this.j) : this.i = i + 7;
+}
+
+abstract class M {
+  get i;
+  get j;
+  int k = 42;
+  foo() => i + j;
+}
+
+class C extends Base with M {
+  int l = 131;
+  C() : super.ctor(1, 13);
+}
+
+main() {
+  C c = new C();
+  Expect.equals(8, c.i);
+  Expect.equals(13, c.j);
+  Expect.equals(42, c.k);
+  Expect.equals(131, c.l);
+  Expect.equals(21, c.foo());
+}