anchor.diff:   * The value of the attribute to be treated as a one-way expression, equivalent
    * to `=>` specification.
    */
  -@deprecated
   class NgOneWay extends DirectiveAnnotation {
     final _mappingSpec = '=>';
     const NgOneWay(String attrName) : super(attrName);
  
positive.code:  * The value of the attribute to be treated as a string, equivalent
   * to `@` specification.
   */
  @deprecated
  class NgAttr extends DirectiveAnnotation {
    final _mappingSpec = '@';
    const NgAttr(String attrName) : super(attrName);
  
negative.code:  * The value of the attribute to be treated as a two-way expression,
   * equivalent to `<=>` specification.
   */
  class NgTwoWay extends DirectiveAnnotation {
    final _mappingSpec = '<=>';
    const NgTwoWay(String attrName) : super(attrName);
  