parse.y: required kwarg without parentheses

* parse.y (parser_yylex): only a newline after label should be
  significant.  [ruby-core:61658] [Bug #9669]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45408 b2dd03c8-39d4-4d8f-98ff-823fe69b080e