This reverts commit e0ed12c7.

* add language version 2.8 in packages/flutter

* enable non-nullable analyzer flag

* Adds default cursor and/or mouseCursor property to a number of widgets.
* Adds `MaterialStateMouseCurrsor`.

This adds a new navigationMode to the MediaQueryData that indicates how focusable controls should behave under different navigation modes, currently with two modes: NavigationMode.traditional, and NavigationMode.directional.

It may seem like focusing a disabled control is not desirable, but this is useful for user interfaces that use DPAD navigation because if a control gets disabled, losing focus is disruptive to the user, and it is difficult to control where the focus will end up unless it is done explicitly.

This PR adds the linux and windows target platform enum values, along with automatically setting the defaultTargetPlatform to the appropriate value on those platforms.

Fixes #31366

This reverts commit 0f8c0da0.

When buildCounter returns null it no longer produces a widget that takes up space.

smartDashesType and smartQuotesType params for text fields to control iOS's smart punctuation feature.

* implicit-casts:false in flutter/lib/src/material

* address review comments

* 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

This PR adds TargetPlatform.macOS to the TargetPlatform enum. This allows us to begin implementation of some adaptive UI based on which target platform is desired.

I haven't updated the tests here, that will come in a follow-up PR.

This flag controls Android's keyboard suggestions on/off

Use assertions to prevent multiline password fields from being created

In #42533, I disabled the up/down arrows for focus navigation in text fields, but we thought of a better way to do it, so this is that better way.

This change reverts the other change, and instead it tests the context of the node in the action to see if it's an EditableText node. If so, then it doesn't do the navigation action.

This disables the arrow key focus navigation for text fields. This was non-standard behavior for text fields, although it remains useful for other kinds of controls.

Fixes #42259

* Adds a new parameter bool opaque to MouseRegion
* The same to RenderMouseRegion and AnnotatedRegionLayer
* Add findAnnotations to Layer 

* add missing trailing commas

* add more missing trailing commas

* add more and more missing trailing commas

* remove splash logic

* update tests

Added docs examples of getting the string from a TextField

This reverts commit 6ad88bd5.