(REXML::Parsers::UltraLightParser#parse): Fix wrong :start_doctype
position.
[Bug #9061] [ruby-dev:47778]
Patch by Ippei Obayashi. Thanks!!!
* test/rexml/parser/test_ultra_light.rb: Add a test for this case.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43693 b2dd03c8-39d4-4d8f-98ff-823fe69b080e