code: function update_std_category_REs(lexer) {
    lexer.whitespaceREs = regexes_for_category(lexer, 'whitespace');
    lexer.linecommentREs = regexes_for_category(lexer, 'linecomment');
    lexer.punctuationREs = regexes_for_category(lexer, 'punctuation');
  }
docs: utility function grabs the 'whitespace', 'linecomment', and
  'punctuation' regexes whenever a dialect is pushed/popped.
  
  note: this is really just a performance optimization since
  these regexes are used so much.