Handle super accesses loaded from .dill

tests/compiler/dart2js/kernel/closed_world_from_dill_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.
 
 // Partial test that the closed world computed from [WorldImpact]s derived from
 // kernel is equivalent to the original computed from resolution.
 library dart2js.kernel.closed_world_from_dill_test;
 
 import 'dart:async';
 import 'dart:io';
@@ skipping 22 matching lines @@
   'main.dart': '''
 
 class ClassWithSetter {
   void set setter(_) {}
 }
 
 class Mixin {
   method1() {}
   method2() {}
   method3() {}
+  method4() {}
+  var field;
+  get property => 0;
+  set property(_) {}
 }
 class Class1 = Object with Mixin;
 class Class2 extends Object with Mixin {
   method3() {}
+  method5() {
+    super.method4();
+    super.property;
+    super.property = null;
+    super.field;
+    super.field = null;
+  }
 }
 
 main() {
   print('Hello World');
   ''.contains; // Trigger member closurization.
   new ClassWithSetter().setter = null;
   new Class1().method1();
   new Class2().method2();
   new Class2().method3();
+  new Class2().method5();
 }
 '''
 };
 
 main(List<String> args) {
   asyncTest(() async {
     await mainInternal(args);
   });
 }
 
@@ skipping 67 matching lines @@
       enqueuer1, enqueuer2, elementEquivalence: equivalence.entityEquivalence,
       typeEquivalence: (ResolutionDartType a, DartType b) {
     return equivalence.typeEquivalence(unalias(a), b);
   }, elementFilter: elementFilter, verbose: arguments.verbose);
 
   checkClosedWorlds(closedWorld1, closedWorld2,
       strategy: equivalence.defaultStrategy, verbose: arguments.verbose);
 
   return ResultKind.success;
 }