anchor.diff:  	| 'interface'
   	| 'iterable'
   	| 'legacycaller'
  -	| 'legacyiterable'
   	| 'maplike'
   	| 'partial'
   	| 'required'
  
positive.code:     http://heycam.github.io/webidl/
  
      Web IDL (Second Edition)
      W3C Editor's Draft 13 November 2014
   */
  grammar WebIDL;
  
  
negative.code: 
  serializerRest
  	: operationRest
  	| '=' serializationPattern ';'
  	| ';'
  ;
  
  serializationPattern
  