anchor.diff:      http://heycam.github.io/webidl/
   
       Web IDL (Second Edition)
  -    W3C Editor's Draft 13 November 2014
  +    W3C Editor's Draft 17 November 2015
    */
   grammar WebIDL;
   
  
positive.code: 	: 'Promise' '<' returnType '>'
  ;
  
  typeSuffix
  	: '[' ']' typeSuffix
  	| '?' typeSuffixStartingWithArray
  	| /* empty */
  ;
  
  typeSuffixStartingWithArray
  	: '[' ']' typeSuffix
  	| /* empty */
  ;
  
  null_
  	: '?'
  	| /* empty */
  
negative.code: 
  serializerRest
  	: operationRest
  	| '=' serializationPattern ';'
  	| ';'
  ;
  
  serializationPattern
  