angular/angular.dart — pull request #1441 by vsavkin (2014-09-09 17:34:09+00:00)
Title: feat(directive_injector): build and maintain a tree of directive injectors

* Change the DirectiveInjector class to store a list of children.
* Change the View store a list of root directive injectors.
* Update ViewPort to keep the view tree and the directive injector tree in sync.