This reverts commit 5fd259be.

Some embeddings might send pointer events with buttons = 0x2 (right-click) for touch or stylus device kinds. If the primary button is synthesized for those events, they won't behave properly. Without this change it's not possible to trigger "secondary tap" events on a TapGestureRecognizer while using a stylus or on an iPad trackpad, since that recognizer will receive buttons = 0x3.

This reverts commit d056500b.

This reverts commit 31de052e.

This reverts commit e2490f29.

This reverts commit 0cbe5975.

This reverts #76179 and relands #73042 with an active timer check fix.
Co-authored-by: David Reveman <reveman@google.com>

This reverts commit 9133deb9.

Timer based pointer event resampling

This provides two improvements to pointer event resampling:

1. PostFrameCallbacks are used instead of scheduling frames. This
avoids unnecessary rendering work when resampling is used.

2. Resampling continues when frames are not produced. I.e. input
events keep being delivered at a fixed frequency even if frame
production is taking a long time.

This fixes #72924
Co-authored-by: David Reveman <reveman@google.com>
Co-authored-by: Tong Mu <dkwingsmt@users.noreply.github.com>

* PointerEvent.local* properties are calculated lazily; other properties are delegated to original.
* Transformed PointerEvent becomes a subclass of its original class.
* Unnamed constructors no longer accepts transform and origin.

* add language version 2.8 in packages/flutter

* enable non-nullable analyzer flag

* Update project.pbxproj files to say Flutter rather than Chromium

Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.

* Update the copyright notice checker to require a standard notice on all files

* Update copyrights on Dart files. (This was a mechanical commit.)

* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.

Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).

* Clean up the copyrights in non-Dart files. (Manual edits.)

Also, make sure templates don't have copyrights.

* Fix some more ORGANIZATIONNAMEs

* add missing trailing commas

* add more missing trailing commas

* add more and more missing trailing commas

Updates documentation and non-public API to use American spellings for
consistency with the rest of the codebase.

No changes to behaviour... other than how it's spelt.

* Revert "Revert "Redo: Add buttons to gestures (#31819)" (#31912)"

This reverts commit 60a1b2b9.

This reverts commit fea2c7d6.

* Revert "Revert "Add buttons to gestures (#30339)" (#31801)"

This reverts commit 8fd7fa49.

* Synthesise kPrimaryButton for unknown devices

* Change TestPointer to a better API

* Correctly synthesise buttons, and add tests

* Add constants `kPrimaryButton`, `kTouchContact` and `kStylusContact`
* PointerDownEvent and PointerMoveEvent will always set the 0x01 bit on buttons

* Fix: ui.PointerChange.remove might contain position change, but we used to expand it into a Cancel and Remove, neither of which allows position change. A Hover event is added, and a test is updated accordingly.
* Fixed the issue where a PointerMoveEvent and a PointerCancelEvent do not receive the correct pressure.
* Refactor the calculation of delta into deltaTo.

Adds support for discrete scroll events, such as those sent by a scroll wheel.

Includes the plumbing to convert, dispatch, and handle these events, as well as
Scrollable support for consuming them.

This implements support for hovering mouse pointers, so that mice connected to Android devices, and ChromeOS devices running Android apps will work properly.

It teaches flutter_test about hover events, which required changing how they are created and used.

Also modifies AnnotatedRegion to allow a region that can be located someplace other than just the origin.

Along with tests for all of the above.

Fixes #5504

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests