Corrects the exact definition in code and docs of ScaleUpDetails delta.

This gesture recognizer can be used to recognize the classic
"onclick" behavior, where each tap in a series fires an event
with an incrementing "count" of how many taps have occurred
in series. This can in turn be used to build widgets that respond
to both tap and double-tap, or for widgets like the YouTube TV
player, where each subsequent tap in a series of >2 taps adjusts
the playhead another 15 seconds.

Fixes https://github.com/flutter/flutter/issues/81657

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 is a re-application of https://github.com/flutter/flutter/pull/81884,
but with https://github.com/flutter/flutter/pull/82834 landed first.

Fixes https://github.com/flutter/flutter/issues/81883

They should have been taking a PointerDownEvent.

This change was originally included in #81884, but that
had to be reverted because it broke Google testss. This
sub-part of that larger change needs to be made first in
order to allow for a phased rollout in a way that won't
break Google tests.

https://github.com/flutter/flutter/issues/81883

This reverts commit e88a387b.

* Gesture recognizer cleanup

1) Make OneSequenceGestureRecognizer.addAllowedPointer()
   call startTrackingPointer(), and change subclasses to
   call super.addAllowedPointer() in place of manually
   calling startTrackingPointer().
2) Fix addAllowedPointer overrides to take PointerDownEvent
   where some were taking PointerEvent.
3) Add API documentation to OneSequenceGestureRecognizer
4) Make the following fields in OneSequenceGestureRecognizer
   private with public getters instead of publicly writable:
   `state`, `primaryPointer`, and `initialPosition`.
5) Clean up gesture recognizer state in
   OneSequenceGestureRecognizer.didStopTrackingLastPointer.

Fixes #81883

This adds support for GestureDetector.onLongPressDown and
GestureDetector.onLongPressCancel, allowing callers to register
interest in the initial pointer contact that might turn into
a long-press (and the associated cancel event if the gesture
loses).

It was incorrectly resetting state when it received a
non-allowed pointer but had already accepted a gesture.

https://github.com/flutter/flutter/issues/81339

* fix PointerUpEvent conversion PointerMoveEvent needs to use the default buttons value.(#73286)

* feat PointerMoveEvent conversion adds test cases

* fix event conversion may modify the original buttons value.

* Update packages/flutter/lib/src/gestures/resampler.dart
Co-authored-by: David Reveman <dreveman@gmail.com>