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

pkg/kernel/test/class_hierarchy_test.dart

Index: pkg/kernel/test/class_hierarchy_test.dart
diff --git a/pkg/kernel/test/class_hierarchy_test.dart b/pkg/kernel/test/class_hierarchy_test.dart
index f57cf02c3ccc72cea5164ab04f3b5134c1b85875..1039035a7a7ad6fec2f8348cf716f5cea89863ec 100644
--- a/pkg/kernel/test/class_hierarchy_test.dart
+++ b/pkg/kernel/test/class_hierarchy_test.dart
@@ -304,6 +304,8 @@ class E = self::D with self::A implements self::B {}
         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 {
@@ -315,16 +317,17 @@ class B extends self::A {
 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