Fix a bug in kernel class hierarchy.

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 'type_algebra.dart';
 
@@ skipping 397 matching lines @@
         result[storeIndex++] = inheritedMember;
         ++j;
       } else {
         result[storeIndex++] = declaredMember;
         ++i;
         ++j; // Move past overridden member.
       }
     }
     // One of the two lists is now exhausted, copy over the remains.
     while (i < declared.length) {
-      result[storeIndex++] = declared[i++];
+      Member declaredMember = declared[i++];
+      if (skipAbstractMembers && declaredMember.isAbstract) continue;
+      result[storeIndex++] = declaredMember;
     }
     while (j < inherited.length) {
-      result[storeIndex++] = inherited[j++];
+      Member inheritedMember = inherited[j++];
+      if (skipAbstractMembers && inheritedMember.isAbstract) continue;
+      result[storeIndex++] = inheritedMember;
     }
     result.length = storeIndex;
     return result;
   }
 
   /// Returns the subset of members in [inherited] for which a member with the
   /// same name does not occur in [declared].
   ///
   /// The input lists must be sorted, and the returned list is sorted.
   static List<Member> _getUnshadowedInheritedMembers(
@@ skipping 411 matching lines @@
 
   /// Non-final instance fields and setters implemented by this class
   /// (declared or inherited).
   List<Member> implementedSetters;
 
   List<Member> interfaceGettersAndCalls;
   List<Member> interfaceSetters;
 
   _ClassInfo(this.classNode);
 }