Remove dart:json
Remove dart:json

BUG= http://dartbug.com/12843
R=floitsch@google.com, fschneider@google.com

Review URL: https://codereview.chromium.org//40323002

git-svn-id: d894903a6691b4329a8535ed724b8f115331b4ef@29240 260f80e4-7a28-3924-810f-c04153c831b5

dart-lang/yaml