* apply upcoming lint cast_nullable_to_non_nullable

* make RenderObjectElement.renderObject non-nullable

Expose GestureBinding.handlePointerEvent, replacing dispatchEvent as the preferred way to dispatch events (#64846)

This reverts commit df833986.

This reverts commit 12b7355d.

* state restoration

* added example

* typos and analyzer

* whitespace

* more typos

* remove unnecessary import

* whitespace

* fix sample code

* tests for restorationmanager and restorationid

* ++

* typo

* tests for bucket, part1

* rename tests

* more tests

* finished tests for service layer

* remove wrong todo

* ++

* review comments

* tests for Unmanaged and regular scope

* RootRestorationScope tests

* typo

* whitespace

* testing framework

* tests for properties

* last set of tests

* analyzer

* typo

* dan review

* whitespace

* ++

* refactor finalizers

* ++

* ++

* dispose guard

* ++

* ++

* dan review

* add manager assert

* ++

* analyzer

* greg review

* fix typo

* Ian & John review

* ian review

* RestorationID -> String

* revert comment

* Make primitives non-nullable in prep for NNBD

This reverts commit aa4b4d35.

* add benchmarkLive flag and tests

* update handlePointerEventRecord doc

* using e2e 0.6.1

* Add input event array support

* Add a tap test

* remove unused import

* remove extra assert

* Fix PointerAddedEvent handling in tester

This reverts commit 2c7e5dd9.

This reverts commit d986fdc3.

* Implement stack trace demangling in the framework.

* move pending timers list code out of assert

* style change
Co-authored-by: Emmanuel Garcia <egarciad@google.com>

* add unit tests

* formatting

* pending timer test

* pending timer assertion test

* add setup and teardown
Co-authored-by: Emmanuel Garcia <egarciad@google.com>

This reverts commit d35671c6.

* Fix FlutterError.onError in debug mode

* update

* fix comments

* add license header

* fix analyzer

* update

* another attempt

* fix test

* fix comment

## Description

Removes the `flutter_test` dependency on `quiver`, instead using the more targeted `clock` and `fake_async` packages.

## Related Issues

https://github.com/flutter/flutter/issues/53908

## Tests

No changes to tests

## Checklist

Before you create this PR confirm that it meets all requirements listed below by checking the relevant checkboxes (`[x]`). This will ensure a smooth and quick review process.

- [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
- [x] I signed the [CLA].
- [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
- [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.
- [x] The analyzer (`flutter analyze --flutter-repo`) does not report any problems on my PR.
- [x] I am willing to follow-up on review comments in a timely manner.

## Breaking Change

Did any tests fail when you ran them? Please read [Handling breaking changes].

- [ ] No, no existing tests failed, so this is *not* a breaking change.
- [x] Yes, this is a breaking change. *If not, delete the remainder of this section.*
   - [x] I wrote a design doc: https://docs.google.com/document/d/1EkkLbECNBwHgddBQAZqEy7iQLTIxR1rgChKzxcLwhio/edit
   - [x] I got input from the developer relations team, specifically from: @RedBrogdon
   - [x] I wrote a migration guide:  https://github.com/flutter/website/pull/3932

<!-- Links -->
[issue database]: https://github.com/flutter/flutter/issues
[Contributor Guide]: https://github.com/flutter/flutter/wiki/Tree-hygiene#overview
[Test Coverage]: https://github.com/flutter/flutter/wiki/Test-coverage-for-package%3Aflutter
[Flutter Style Guide]: https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo
[Features we expect every widget to implement]: https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene
[Handling breaking changes]: https://github.com/flutter/flutter/wiki/Tree-hygiene#handling-breaking-changes

fix KeySet.hashCode; enable multiple web tests