Fixes for super tearoff in constructor

tests/language_strong/super_from_constructor_test.dart

 // Copyright (c) 2017, 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";
 
 final results = [];
 
+int invoke(int f()) => f();
+
 class Base {
   var f;
+  var z;
+
   m(x) => results.add(x);
+
+  int g() {
+    return 42;
+  }
 }
 
 class C extends Base {
   final Iterable _iter;
 
   C(this._iter) {
     _iter.map((x) => super.m(x)).toList();
     super.f = _iter;
+    z = invoke(super.g);
+  }
+
+  int g() {
+    return -1;
   }
 }
 
 main() {
   var c = new C([1, 2, 3]);
   Expect.listEquals(results, [1, 2, 3]);
   Expect.listEquals(c.f, [1, 2, 3]);
+  Expect.equals(42, c.z);
 }