Ruby

• transcode.c (sym_html): new variable.
  (sym_text): ditto.
  (sym_attr): ditto.
  (econv_opts): check :html=>:text and :html=>:attr.
  (Init_transcode): initialize the above variables.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@19180 b2dd03c8-39d4-4d8f-98ff-823fe69b080e