* Reland "Nnbd widgets (#64672)"

This reverts commit 127e6790.

* remove non-nullable enforcement on AsyncSnapshot

* make data param non-nullable for AsyncSnapshot.withData

* make some Text params non-nullable

[flutter_tools] handle terminals that do not support single char mode in Terminal.promptForCharInput (#65418)

Some terminals stdin do not support single char mode (like an emacs terminal buffer apparently). If this is the case, then the presented choice values would always have an appended newline \n which would prevent us from finding the value in the listed index (or using it as a signal for the default choice). To fix, treat '' as the default choice and always trim the choice value.

While this has seemingly always been broken, it wasn't noticeable until the multi-device selection prompt was added a few months ago.

Fixes #65267

Because the Status spinner was only created on setup, the second stop would asset/crash.

Fixes #65449

Currently these tests are taking CI time without providing any value, because there is no verification that network connectivity is avoided. This is better covered by a unit test that verifies that --offline is passed to pub.

097facfac Roll Dart SDK from 4bf1f624d06e to b6f67aa2cc72 (1 revision) (flutter/engine#21139) (#65712)

This reverts commit 33f79950.

* fuchsia_remote_debug_protocol allows open port on remote device

Allows defining a port forwarding function for which the accessible
port is not on the host device. Examples include tunneling solutions
where a tunneling program on the same device as the Dart VM exposes
an open port through which it tunnels connections to the VM.

* Move ssh-specific comment to SshPortForwarder

* Adds a new web benchmark bench_mouse_region_mixed_grid_hover

Bug fix where MouseScrollWheel zoom in flutter-web does not execute onInteraction functions (#65313)

This reverts commit ccd4f6dd.