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
I think people new to promises, angular etc will find this example easier to understand with concrete identifiers from a simple use-case. The existing naming could be confused with promise/angular functionality (`promise` in the template, `resolved` etc).
Also I made `resolve` private, as then it's clear what we're exposing for the template.