Sync with 434308a
Sync with 434308a

Synced with angular/angular.io master branch, commit 434308a:
https://github.com/angular/angular.io/tree/434308ab1b3eb6aeb66382e1ca615358827ac859/public/docs/_examples/hierarchical-dependency-injection/dart

angular-examples/hierarchical-dependency-injection,googlearchive/hierarchical-dependency-injection,angular-examples/hierarchical-dependency-injection,googlearchive/hierarchical-dependency-injection