anchor.diff:  
     @override
     List<MethodElement> get methods {
  -    List<MethodElement> methods = element.methods;
  -    List<MethodElement> members = new List<MethodElement>(methods.length);
  -    for (int i = 0; i < methods.length; i++) {
  -      members[i] = MethodMember.from(methods[i], this);
  -    }
  -    return members;
  +    if (_methods == null) {
  +      List<MethodElement> methods = element.methods;
  +      List<MethodElement> members = new List<MethodElement>(methods.length);
  +      for (int i = 0; i < methods.length; i++) {
  +        members[i] = MethodMember.from(methods[i], this);
  +      }
  +      _methods = members;
  +    }
  +    return _methods;
     }
   
     @override
  
positive.code:   final List<FunctionTypeAliasElement> prunedTypedefs;
  
    /**
     * Initialize a newly created type to be declared by the given [element].
     */
    InterfaceTypeImpl(ClassElement element, [this.prunedTypedefs])
  
negative.code:   InterfaceTypeImpl._(Element element, String name, this.prunedTypedefs)
        : super(element, name);
  
  
    @override
    List<PropertyAccessorElement> get accessors {
      if (_accessors == null) {
        List<PropertyAccessorElement> accessors = element.accessors;
        List<PropertyAccessorElement> members =
        new List<PropertyAccessorElement>(accessors.length);
        for (int i = 0; i < accessors.length; i++) {
          members[i] = PropertyAccessorMember.from(accessors[i], this);
        }
        _accessors = members;
      }
      return _accessors;
    }
  
  
    @override
    List<ConstructorElement> get constructors {
      if (_constructors == null) {
        List<ConstructorElement> constructors = element.constructors;
        List<ConstructorElement> members =
            new List<ConstructorElement>(constructors.length);
        for (int i = 0; i < constructors.length; i++) {
          members[i] = ConstructorMember.from(constructors[i], this);
        }
        _constructors = members;
      }
      return _constructors;
    }
  
    @override
  