anchor.diff:  Package:                        'package' {this.IsStrictMode()}?;
   Protected:                      'protected' {this.IsStrictMode()}?;
   Static:                         'static' {this.IsStrictMode()}?;
  -Yield:                          'yield' {this.IsStrictMode()}?;
   
   /// Identifier Names and Identifiers
   
  
positive.code: 
  Async:                          'async';
  Await:                          'await';
  
  /// The following tokens are also considered to be FutureReservedWords
  /// when parsing strict mode
  
negative.code: 
  fragment RegularExpressionBackslashSequence
      : '\\' ~[\r\n\u2028\u2029]
      ;
  