parse.y: fix fluent interface identifier

* parse.y (parser_yylex): dispatch newline and space at fluent
  interface, so that the following identifier does not include the
  space.  [ruby-dev:48684] [Bug #10411]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48126 b2dd03c8-39d4-4d8f-98ff-823fe69b080e