This reverts commit 28f2c96a.

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 2132a0c7.

Use strut box heights to calculate selection rectangles in order to ensure that they remain within visible bounds (#50354)

This reverts commit 69080e07.

This implements VisualDensity changes for text fields*. By default, the layout of the text field does not change.

If the ThemeData.visualDensity is set to a value other than zero, then the density of the UI will increase or decrease. See the VisualDensity docs for more information.

(*In reality, the changes are on the InputDecorator class, not on the text field.)

I also fixed a problem that I think I found with _Decoration where it doesn't compare isDense or isCollapsed as part of its operator==.

This PR is a follow up of https://github.com/flutter/flutter/pull/42640
Some changes of that PR includes redundant changes using FlutterError.fromParts constructor even though it's not necessary.

Some minor changes are:

- Remove one unnecessary todo
- Fix indent consistencies

* Feature: allow minLines in SelectableText

* Adds an opt-in flag to fix floating snackbar's offset when no floating action button is present. This flag will be removed once the migration for the fix is complete.
Co-authored-by: filaps <filip1997.28@mail.ru>

* Add ButtonBar.overflowButtonSpacing

* Add AlertDialog overflow button spacing functionality

Revert "AlertDialog.actionsOverflowButtonSpacing and ButtonBar.overflowButtonSpacing (#50609)" (#50674)

* Add ButtonBar.overflowButtonSpacing

* Add AlertDialog overflow button spacing functionality

Revert "Revert "Reduced code duplication in ink_splash.dart, ink_ripple.dart (#49480)" (#50502)" (#50512)

This reverts commit 9bc0e6a9.

Revert "Fix SnackBar clipping when it is floating due to FloatingActionButton positioning (#47616)" (#50516)

This reverts commit 801a6a7e.

This reverts commit 90206427.

This PR modifies the existing API docs samples to use DartPad so that all of the samples are now interactive apps on the API docs site.

It also removes the restriction for the max width of the description area so that the dartpad region can expand horizontally.

I updated the first paragraph on the API docs to indicate that Flutter is more than just mobile now (same text as the README.md at the top level).

I modified a few of the examples so that they looked nicer, and fit better on the page.

I added the sample description text above each DartPad instance, since that often defines the context of the example.

I removed animations and images when they were redundant with the sample content. There were a few that made sense to keep, so I did.