feat(router): implement CandDeactivate

modules/@angular/router/src/index.ts

@@ -1,6 +1,6 @@
 export { Router } from './router';
 export { UrlSerializer, DefaultUrlSerializer } from './url_serializer';
-export { RouterState, ActivatedRoute } from './router_state';
+export { RouterState, ActivatedRoute, RouterStateSnapshot, ActivatedRouteSnapshot } from './router_state';
 export { UrlTree, UrlSegment} from './url_tree';
 export { RouterOutletMap } from './router_outlet_map';
 export { RouterConfig, Route } from './config';