Implement more super calls.

test/kernel/regression/super_operator.dart

 // Copyright (c) 2016, 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.md file.
 
 class A {
-  A(this.x);
+  operator + (String s) => null;
+
+  operator [] (i) => null;
+
+  operator []= (i, val) {}
 }
 
 class B extends A {
-  const B();
+  operator + (String s) => super + ("${s}${s}");
+
+  operator [] (i) => super[i];
+
+  operator []= (i, val) => super[i++] += val;
 }
 
-main() {
-  new B();
-  const B();
+class Autobianchi {
+  g() => super[0];
 }