* lib/rexml/entity.rb: keep the entity size within the limitation.
  reported by Willis Vandevanter <will@silentrobots.com> and
  patched by nahi.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48161 b2dd03c8-39d4-4d8f-98ff-823fe69b080e