Ruby

merges r27855 from trunk into ruby_1_9_2.¶

• ext/psych/lib/psych/emitter.rb: removing unused file.
• ext/psych/lib/psych/json/tree_builder.rb: moving tree builder to an
  event based external class.
• ext/psych/lib/psych/tree_builder.rb: adding an end_stream event.
• ext/psych/lib/psych/visitors/json_tree.rb: using event based AST
  builder.
• ext/psych/lib/psych/visitors/yaml_tree.rb: using event based AST
  builder.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_2@27970 b2dd03c8-39d4-4d8f-98ff-823fe69b080e