Fix VM bug with super-constructor invocation and mixins.

tests/language/constructor_with_mixin_test.dart

+// Copyright (c) 2015, 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 super constructor invocation with mixins.
+// Regression test for issue dartbug.com/22604
+
+import "package:expect/expect.dart";
+
+var a_count = 0;
+var b_count = 0;
+
+class A {
+  final int x;
+  A(int this.x) {
+    a_count++;
+  }
+}
+
+class I { }
+
+class B extends A with I {
+  int y;
+
+  B(int xx) : super(xx), y = 13 {
+    b_count++;
+  }
+}
+
+void main() {
+  var b = new B(17);
+  Expect.equals(1, a_count);
+  Expect.equals(1, b_count);
+}
+