Implement implicit constructors in mixin applications.

tests/language/mixin_super_constructor_positionals_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 this.i, [int this.j = 10]);
+}
+
+abstract class M {
+  get i;
+  get j;
+  int k = 42;
+  foo() => i + j;
+}
+
+class C extends Base with M {
+  int l = 131;
+  C.foo() : super.ctor(1, 13);
+  C.bar() : super.ctor(1);
+}
+
+main() {
+  C c1 = new C.foo();
+  Expect.equals(1, c1.i);
+  Expect.equals(13, c1.j);
+  Expect.equals(14, c1.foo());
+  Expect.equals(42, c1.k);
+  Expect.equals(131, c1.l);
+  C c2 = new C.bar();
+  Expect.equals(1, c2.i);
+  Expect.equals(10, c2.j);
+  Expect.equals(11, c2.foo());
+  Expect.equals(42, c2.k);
+  Expect.equals(131, c2.l);
+}