* lib/cgi/util.rb(CGI.escapeHTML): performance improvement.
  thank you @bbxiao1 via
  https://github.com/ruby/ruby/pull/333

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41431 b2dd03c8-39d4-4d8f-98ff-823fe69b080e