Revert "Fix forEachOverridePair in the case where the class in question is abstract."

pkg/kernel/test/class_hierarchy_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:kernel/ast.dart';
 import 'package:kernel/class_hierarchy.dart';
 import 'package:kernel/core_types.dart';
 import 'package:kernel/src/incremental_class_hierarchy.dart';
 import 'package:kernel/testing/mock_sdk_program.dart';
 import 'package:kernel/text/ast_to_text.dart';
@@ skipping 286 matching lines @@
         procedures: [newEmptyMethod('foo')]));
     var b = addClass(new Class(
         name: 'B',
         supertype: a.asThisSupertype,
         procedures: [newEmptyMethod('foo', isAbstract: true)]));
     var c = addClass(new Class(
         name: 'C',
         supertype: a.asThisSupertype,
         procedures: [newEmptyMethod('foo', isAbstract: true)],
         isAbstract: true));
+    var d = addClass(new Class(name: 'D', supertype: b.asThisSupertype));
+    var e = addClass(new Class(name: 'E', supertype: c.asThisSupertype));
 
     _assertTestLibraryText('''
 class A {
   method foo() → void {}
 }
 class B extends self::A {
   abstract method foo() → void;
 }
 abstract class C extends self::A {
   abstract method foo() → void;
 }
+class D extends self::B {}
+class E extends self::C {}
 ''');
 
     _assertOverridePairs(b, [
       'test::A::foo overrides test::B::foo',
       'test::B::foo overrides test::A::foo'
     ]);
-    _assertOverridePairs(c, [
-      'test::A::foo overrides test::C::foo',
-      'test::C::foo overrides test::A::foo'
-    ]);
+    _assertOverridePairs(c, ['test::C::foo overrides test::A::foo']);
+    _assertOverridePairs(d, ['test::A::foo overrides test::B::foo']);
+    _assertOverridePairs(e, ['test::A::foo overrides test::C::foo']);
   }
 
   /// 3. A non-abstract member is inherited from a superclass, and it overrides
   /// an abstract member declared in this class.
   void test_forEachOverridePair_supertypeOverridesThisAbstract() {
     var a = addClass(new Class(
         name: 'A',
         supertype: objectSuper,
         procedures: [newEmptyMethod('foo'), newEmptyMethod('bar')]));
     var b = addClass(new Class(
@@ skipping 1001 matching lines @@
     actualText = actualText.replaceAll(' extends core::Object', '');
 
     if (actualText != expectedText) {
       print('-------- Actual --------');
       print(actualText + '------------------------');
     }
 
     expect(actualText, expectedText);
   }
 }