anchor.diff:    final Name name;
     ClassMember declaredMember;
     ClassMember declaredSetter;
  +  ClassMember mixedInMember;
  +  ClassMember mixedInSetter;
     ClassMember extendedMember;
     ClassMember extendedSetter;
     List<ClassMember> implementedMembers;
  
positive.code:       : assert(!declaredMember.forSetter),
          this.name = declaredMember.name;
  
    Tuple.extendMember(this.extendedMember)
        : assert(!extendedMember.forSetter),
          this.name = extendedMember.name;
  
negative.code:       }
        if (mixin is ClassBuilder) {
          scope = mixin.scope.computeMixinScope();
  
          for (MemberBuilder memberBuilder in scope.localMembers) {
            for (ClassMember classMember in memberBuilder.localMembers) {
              Tuple tuple = memberMap[classMember.name];
              if (tuple == null) {
                memberMap[classMember.name] = new Tuple.mixInMember(classMember);
              } else {
                tuple.mixedInMember = classMember;
              }
            }
            for (ClassMember classMember in memberBuilder.localSetters) {
              Tuple tuple = memberMap[classMember.name];
              if (tuple == null) {
                memberMap[classMember.name] = new Tuple.mixInSetter(classMember);
              } else {
                tuple.mixedInSetter = classMember;
              }
            }
          }
  
          for (MemberBuilder memberBuilder in scope.localSetters) {
            for (ClassMember classMember in memberBuilder.localMembers) {
              Tuple tuple = memberMap[classMember.name];
              if (tuple == null) {
                memberMap[classMember.name] = new Tuple.mixInMember(classMember);
              } else {
                tuple.mixedInMember = classMember;
              }
            }
            for (ClassMember classMember in memberBuilder.localSetters) {
              Tuple tuple = memberMap[classMember.name];
              if (tuple == null) {
                memberMap[classMember.name] = new Tuple.mixInSetter(classMember);
              } else {
                tuple.mixedInSetter = classMember;
              }
            }
          }
        }
      }
  