* lifecycle-hooks: copy latest to cache
* docs(lifecycle-hooks): post-RC5 Dart resync
- TS prose: removed mention of `routerOnActivate` which no longer
exists in the new router.
- TS improvements to the sample code have also been propagated to the
Dart sample.
Contributes to #2077.
E2E tests pass now.
* post-review updates
Mainly copyedits, but also
- Dart .jade extends TS .jade file with minor overrides
- Significant update of example code (so it matches the ts example in its
appearance and behavior).
- Tweaks to Dart code.
- A few extra/corrected mixin definitions in `_util-fns.jade`.
