Update the Angular 2 transformer to recognize
`package:angular2/platform/browser.dart` as the library which exports
the `bootstrap` function.
Update playground, examples, benchmarks, & tests to import bootstrap from
platform/browser.
Closes#7647
TL;DR: Modify pubspec.yaml files to use the recommended "targeted"
transformers. The unified "simple" angular2 transformer still works as
always, but we want to encourage use of the targeted transformers
whereever possible.
See [the wiki](https://github.com/angular/angular/wiki/Advanced-Transformer-Configuration)
for details about targeted transformers.
See #1872
The hello_world app used to measure Dart payload size was broken by a
change in
7ae23adaff.
This breakage does not materially affect the size of the generated code,
(before fix: 298819, after fix: 298825), and since it was a runtime
error it was not noticed & not a problem.
Update the app to work again.
Closes#7358
Import dependencies from `angular2/angular2.dart` in `hello_world` to
ensure that any size regressions are caught by our checks.
Update to avoid regressions like #5419.
Closes#5394