v0.4.12+3

BUG=

Review URL: https://chromiumcodereview.appspot.com//17716003

bump spec

publish 0.4.12 - breaking changes for 0.5.20

v0.4.11+2

BUG=

Review URL: https://chromiumcodereview.appspot.com//16865013

v0.4.11+1

BUG=

Review URL: https://chromiumcodereview.appspot.com//16739012

upgrades for version 0.5.16

Review URL: https://chromiumcodereview.appspot.com//16668006

Fixes in WebComponent to match the latest dart:html in 0.5.14.3

Due to bug http://dartbug.com/11154, we didn't detect this on the last roll.

Review URL: https://chromiumcodereview.appspot.com//16677004

v0.4.9+5

BUG=

Review URL: https://chromiumcodereview.appspot.com//16557003

bump version