This previously had no coverage.
* test/webrick/test_filehandler.rb (test_erbhandler): new test
* test/webrick/webrick.rhtml: new file for test
[Misc #14216]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61399 b2dd03c8-39d4-4d8f-98ff-823fe69b080e