[mdv] implement Node.createBinding and Node.createBindings port of https://github.com/Polymer/mdv/commit/95c4eca5a89ed3d04af1c6607a61f49d35d05ca6, https://github.com/Polymer/mdv/commit/3a0d2f302d474cd175d7fe49b278f928a019d053
[mdv] implement Node.createBinding and Node.createBindings
port of
https://github.com/Polymer/mdv/commit/95c4eca5a89ed3d04af1c6607a61f49d35d05ca6, https://github.com/Polymer/mdv/commit/3a0d2f302d474cd175d7fe49b278f928a019d053

BUG=
R=sigmund@google.com

Review URL: https://codereview.chromium.org//20149004

git-svn-id: dae132d4ca6f88932ad8a9ec3641c81ad1592b72@25485 260f80e4-7a28-3924-810f-c04153c831b5

dart-archive/observe,dart-lang/observe