This reverts commit cde78c16.

This re-lands #20496 and #21780 after fixing the semantics-enabling code that was causing the post-submit web_smoke_test to fail.

Below is the description from the original PR:

This is a PR for converting the dart:ui code in the engine to use a multi-window API. The goal here is to convert from the window singleton to an API that has the concept of multiple windows. Also, I'm matching up the new PlatformDispatcher class to talk directly to the PlatformConfiguration class in the engine. I'm not attempting to actually enable creating multiple windows here, just migrate to an API that has a concept of multiple windows. The multi-window API in this PR currently only ever creates one window.

The design doc for this change is here.

The major changes in this PR:

Move the platfom-specific attributes out of Window, and into the new PlatformDispatcher class that holds all of the platform state, so that the platform code need only update the configuration on this class.
Create FlutterView, FlutterWindow, and SingletonFlutterWindow classes to separate out the concepts of a view (of which there may be multiple in a window), a window (of which there may be multiple on a screen, and they host views), and a window where there is only ever expected to be one (this hosts the entire API of the former Window class, and will eventually be the type of the window singleton).
Next step after this PR lands:

Remove the Window class entirely (it is replaced by SingletonFlutterWindow). Some minor changes in the Framework are needed to switch to using SingletonFlutterWindow directly first.

The Window class still exists in this PR, but will be removed as soon as the framework is converted to point to the SingletonFlutterWindow class instead. They share the same API, just have different names (Window is currently a subclass of SingletonFlutterWindow). The intention is that the Window name will be freed up to use as a widget class name in the framework for managing windows. The singleton called window will remain, and keep the same API it has now.

* Revert "Fix documentation build for window changes. (#21780)"

This reverts commit 931a0468.

* Revert "Migration to PlatformDispatcher and multi-window (#20496)"

This reverts commit 85b0031f.

This is to unblock a Dart -> engine roll.

This is a PR for converting the dart:ui code in the engine to use a multi-window API. The goal here is to convert from the window singleton to an API that has the concept of multiple windows. Also, I'm matching up the new PlatformDispatcher class to talk directly to the PlatformConfiguration class in the engine. I'm not attempting to actually enable creating multiple windows here, just migrate to an API that has a concept of multiple windows. The multi-window API in this PR currently only ever creates one window.

The design doc for this change is here.

The major changes in this PR:

Move the platfom-specific attributes out of Window, and into the new PlatformDispatcher class that holds all of the platform state, so that the platform code need only update the configuration on this class.
Create FlutterView, FlutterWindow, and SingletonFlutterWindow classes to separate out the concepts of a view (of which there may be multiple in a window), a window (of which there may be multiple on a screen, and they host views), and a window where there is only ever expected to be one (this hosts the entire API of the former Window class, and will eventually be the type of the window singleton).
Next step after this PR lands:

Remove the Window class entirely (it is replaced by SingletonFlutterWindow). Some minor changes in the Framework are needed to switch to using SingletonFlutterWindow directly first.

The Window class still exists in this PR, but will be removed as soon as the framework is converted to point to the SingletonFlutterWindow class instead. They share the same API, just have different names (Window is currently a subclass of SingletonFlutterWindow). The intention is that the Window name will be freed up to use as a widget class name in the framework for managing windows. The singleton called window will remain, and keep the same API it has now.

for Android and iOS and remove offset from scenario_app test for iOS and Android.

Cleans up header order/grouping for consistency: associated header, C/C++ system/standard library headers, library headers, platform-specific #includes.

Adds <cstring> where strlen, memcpy are being used: there are a bunch of places we use them transitively.

Applies linter-required cleanups. Disables linter on one file due to included RapidJson header. See https://github.com/flutter/flutter/issues/65676

This patch does not cover flutter/shell/platform/darwin. There's a separate, slightly more intensive cleanup for those in progress.

This speculatively disables the ApplicationLifecycle Scenarios iOS tests
which continue to fail after being re-enabled in flutter/engine#21087.

Related P0 issue: https://github.com/flutter/flutter/issues/61620

Add copyright headers in a few files where they were missing.

Trim trailing blank comment line where present, for consistency with
other engine code.

Use the standard libtxt copyright header in one file where it differed
(extra (C) and comma compared to other files in libtxt).

This also amends tools/const_finder/test/const_finder_test.dart to look
for a const an additional four lines down to account for the copyright
header added to the test fixture.

This re-enables the iOS Scenarios tests which have been flaky in the
last couple days.

Disabling two tests where we've seen the flakes:
* AppLifecycleTests testFlutterViewControllerDetachingSendsApplicationLifecycle
* FlutterViewControllerInitialRouteTest testSettingInitialRoute

This reverts commit 0c6c265a.

This disables the macOS Scenarios app tests until a fix for the current
flakiness is found.

This also reverts commit 55d447a1 where
one test was previously disabled. However, another started failing soon
after, so instead we disable the whole suite here.

This disables the macOS Scenarios app test
testFlutterViewControllerDetachingSendsApplicationLifecycle
until a fix for the flakiness is found.

Related issue: https://github.com/flutter/flutter/issues/61620

This deletes old LUCI build scripts that have been unused since
https://flutter-review.googlesource.com/c/recipes/+/3160

This reverts commit 575a5194.

Lazy async stacks were already enabled by-default in AOT mode in [0] - which made the
gen_snapshot invocations use "--lazy-async-stacks --no-causal-async-stacks".

This change does the same with the engine defaults, which makes this be enabled
by-default in JIT mode as well.

See go/dart-10x-faster-async for more information.

This is a re-land: A fix for what we believe to have caused the last revert has landed upstream in Dart in dart-lang/sdk@0004589

[0] flutter/flutter@3478232

This reverts commit 4de62c7c.

This reverts commit d16ba48e.

I just made a pass on the scenario scripts so that they can be more easily run from the scenario directory, set the ANDROID_HOME correctly, and generally fixed lint errors.

Also compile_android_aot.sh didn't appear to work, and I think I fixed it (it builds now).

This converts the ci/format.sh script to a Dart script that uses process_runner and isolates to multi-process the clang-format, diffs, and grepping needed to do the formatting changes.

It also will (by default) only check the formatting of changed files.

The user can optionally check all files (--all-files) or do only some types of checks with --check. --verbose prints the versions of the tools used for Clang format and Java format.

Specifying --fix will cause any formatting errors that would have been detected to be fixed.