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

pkg/kernel/lib/class_hierarchy.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 file.
 library kernel.class_hierarchy;
 
 import 'ast.dart';
 import 'dart:math';
 import 'dart:typed_data';
 import 'src/heap.dart';
 import 'type_algebra.dart';
@@ skipping 399 matching lines @@
       var superGetters = getInterfaceMembers(superclass);
       var superSetters = getInterfaceMembers(superclass, setters: true);
       _reportOverrides(info.implementedGettersAndCalls, superGetters, callback);
       _reportOverrides(info.declaredGettersAndCalls, superGetters, callback,
           onlyAbstract: true);
       _reportOverrides(info.implementedSetters, superSetters, callback,
           isSetter: true);
       _reportOverrides(info.declaredSetters, superSetters, callback,
           isSetter: true, onlyAbstract: true);
     }
-    // If a class declares an abstract method M whose
-    // implementation M' is inherited from the superclass, then the inherited
-    // method M' overrides the declared method M.
-    // This flies in the face of conventional override logic, but is necessary
-    // because an instance of the class will contain the method M' which can
-    // be invoked through the interface of M.
-    // Note that [_reportOverrides] does not report self-overrides, so in
-    // most cases these calls will just scan both lists and report nothing.
-    _reportOverrides(info.implementedGettersAndCalls,
-        info.declaredGettersAndCalls, callback);
-    _reportOverrides(info.implementedSetters, info.declaredSetters, callback,
-        isSetter: true);
+    if (!class_.isAbstract) {
+      // If a non-abstract class declares an abstract method M whose
+      // implementation M' is inherited from the superclass, then the inherited
+      // method M' overrides the declared method M.
+      // This flies in the face of conventional override logic, but is necessary
+      // because an instance of the class will contain the method M' which can
+      // be invoked through the interface of M.
+      // Note that [_reportOverrides] does not report self-overrides, so in
+      // most cases these calls will just scan both lists and report nothing.
+      _reportOverrides(info.implementedGettersAndCalls,
+          info.declaredGettersAndCalls, callback);
+      _reportOverrides(info.implementedSetters, info.declaredSetters, callback,
+          isSetter: true);
+    }
   }
 
   @override
   void forEachCrossOverridePair(Class class_,
       callback(Member declaredMember, Member interfaceMember, bool isSetter),
       {bool crossGettersSetters: false}) {
     _ClassInfo info = _infoFor[class_];
     for (var supertype in class_.supers) {
       var superclass = supertype.classNode;
       var superGetters = getInterfaceMembers(superclass);
@@ skipping 727 matching lines @@
 class _LubHeap extends Heap<_ClassInfo> {
   @override
   bool sortsBefore(_ClassInfo a, _ClassInfo b) => sortsBeforeStatic(a, b);
 
   static bool sortsBeforeStatic(_ClassInfo a, _ClassInfo b) {
     if (a.depth > b.depth) return true;
     if (a.depth < b.depth) return false;
     return a.topologicalIndex < b.topologicalIndex;
   }
 }