This reverts commit 5fd259be.

This reverts commit d056500b.

This reverts commit 31de052e.

This reverts commit e2490f29.

This relands #68587

This reverts commit bde85ea3.

* Fix mutiple pointers bug

* Add unit test case

* Remove unnecessary map clone

* 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 "OneSequenceRecognizer.resolvePointer". Fix DragGestureRecognizer crash on multiple pointers (#39017)

* Add drag tests

* Add resolvePointer

* Correct monodrag implementation

* Fix some addTearDown

This reverts commit 572f349f.

- A refactor that moves the semantics declaration from detectors to recognizers to allow custom recognizers to respond to semantic gectures.
- Renames all handlers related to semantics from Gesture* to Semantics*.

Corects a bnuch of typeos throuhgout teh Fluter codebsae.

Made use of the `misspell` tool:
https://github.com/client9/misspell

* 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

This reverts commit 727e7e82.

* Callbacks of tap, long press, drag, and double tap GR respond to only primary events.
* Add "secondary" callbacks to tap.
* Recognizers only compete on events if there are any related callbacks.
* Add "kSecondaryButton" constant.

* add trailing commas on list/map/parameters

* add trailing commas on Invocation with nb of arg>1

* add commas for widget containing widgets

* add trailing commas if instantiation contains trailing comma

* revert bad change

Breaks the moveBy call from drag and dragFrom into two separate calls and changes the default behavior of DragStartBehavior to DragStartBehavior.start (#26438)

* Breaking change which sets the default DragStartBehavior to DragStartBehavior.start and changes WidgetTester.drag and WidgetTester.dragFrom by breaking the moveBy function call into multiple pieces.

* the onStart callback will report the location of the pointer where it wins the gesture arena by default instead of the pointer down location. Fixes all tests related to changing this default value.

This reverts commit 08538f91.

* Adds start behavior option to the drag gesture recognizer and makes it the default option when a drag gesture recognizer is created. Also fixes all the tests to work correctly with the new default behavior.

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

* monodrag fix

* added a test

* added test and changes

* fixed import

* removed comments