* parse.y (words, symbols, qwords, qsymbols): unify empty list and
  non-empty list.

* parse.y (parser_parse_string): always dispatch a word separator
  at the beginning of list literals.
  [ruby-core:83871] [Bug #14126]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60892 b2dd03c8-39d4-4d8f-98ff-823fe69b080e