ext/json/lib/json/pure/parser.rb, ext/openssl/lib/openssl/x509.rb,
ext/win32ole/sample/olegen.rb, lib/date/format.rb, lib/irb/context.rb,
lib/irb/workspace.rb, lib/net/http.rb, lib/net/imap.rb,
lib/rdoc/generator.rb, lib/rdoc/markup/to_html.rb,
lib/rdoc/markup/to_latex.rb, lib/rdoc/parsers/parse_c.rb,
lib/rdoc/ri/formatter.rb, lib/rexml/parsers/baseparser.rb,
lib/rexml/quickpath.rb, lib/rexml/text.rb, lib/rss/parser.rb,
lib/uri/common.rb, lib/uri/generic.rb, lib/webrick/httpresponse.rb,
lib/webrick/httpservlet/filehandler.rb, lib/yaml/baseemitter.rb,
lib/yaml/encoding.rb: performance tuning arround String#gsub.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@15442 b2dd03c8-39d4-4d8f-98ff-823fe69b080e