Implement deferred libraries to work with dependency injection and other
angular codegen. This is done by not initializing the library in the parent
ng_deps file when it is declared as deferred, rewriting the import and,
chaining a future that initializes the library in any files that are using
deferred libraries which need angular codegen.
Remove reflector parameter from initReflector method to simplify ng_deps for reflection
initialization. It wasn't used and was added for testability, but wasn't used. This
keeps the interface simplier.
Add a transformer for `di` which generates `.ng_deps.dart` files for all
`.dart` files it is run on. These `.ng_deps.dart` files register
metadata for any `@Injectable` classes.
Fix unit tests for changes introduced by the di transformer.
When using `pub (build|serve) --mode=ngstatic`, we will also generate
getters and setters, parse templates, and remove import of `dart:mirrors`
in the Angular transform. Because this is still relatively immature, we
use the mode to keep it opt-in for now.
Closes#700