This reverts commit 2a5aa294.

Additionally, fix a few NNBD issues.

Fixes https://github.com/flutter/flutter/issues/70408

This reverts commit 8749d955.

* Disable failing test due to SDK issue

* Disable failing debugger and hot reload windows tests

In principle this is backwards compatible; I just merged all the classes into one and deprecated everything that became redundant as a result.

Address comment in https://github.com/flutter/flutter/pull/66386/files#r522671103

* 03ff8a409 TBR: remove the extra values which was overshadowing the test result (flutter/engine#22483)

* e9b6a428f Roll Skia from a06b63c56ecd to 8ead30d51c86 (1 revision) (flutter/engine#22487)

* ee700513e Roll Fuchsia Linux SDK from fULjPqtx9... to B4PaMsNWM... (flutter/engine#22490)

* 4cbb684ef Roll Dart SDK from 3e502e0c7e04 to 41893ff76b0f (1 revision) (flutter/engine#22491)

* 38b6c22d5 PlatformViewIOS CreateExternalViewEmbedder refactor (flutter/engine#22353)

* bbcf19ad1 Roll Skia from 8ead30d51c86 to 011218edb590 (4 revisions) (flutter/engine#22493)

[flutter_tools] use initially parsed package config for language version, sound mode determination (#70323)

Revert "[integration_test] Add a `run` method for proper reporting of test results (#70075)" (#70466)

This reverts commit af5eb3b9.

Change the semantics of Actions.invoke so that if the action it finds is disabled, then it keeps looking for an ancestor Actions widgets that has a matching intent where the action is not disabled.

[flutter_tools] remove branch migration and standardize constructor style for version interface (#70058)

Migrate flutter_localizations to null safety.

This reverts commit a0ec4d67.

Unit tests that cover their translations are also added.

This allows the two videos in the demo to play simultaneously
(matching the behavior from before the recent upgrade to the
video player plugin)

This reverts usages of the binding's platformDispatcher to use window again temporarily, because there isn't a TestPlatformDispatcher yet, and so some tests were failing because they mocked the TestWindow to return certain things (locales) that were returning the real values instead of the test values.

Once I've created a TestPlatformDispatcher to allow fake data to be passed to it, we can go back to using the platformDispatcher in all of these places

This reverts commit 1f0df545.

This reverts commit 15d2d8a8.