When attempting to release the Flutter 3.24.1 hotfix, Flutter framework post submits failed due to the following error:

```
���ERROR #1���������������������������������������������������������������������
� UNEXPECTED ERROR!
� Exception: Found unexpected binary in cache: /Volumes/Work/s/w/ir/x/w/flutter/bin/cache/artifacts/engine/ios-release/extension_safe/Flutter.xcframework/ios-arm64_x86_64-simulator/dSYMs/Flutter.framework.dSYM/Contents/Resources/DWARF/Flutter
� #0      verifyExist (file:///Volumes/Work/s/w/ir/x/w/flutter/dev/bots/suite_runners/run_verify_binaries_codesigned_tests.dart:150:12)
� <asynchronous suspension>
� #1      verifyCodesignedTestRunner (file:///Volumes/Work/s/w/ir/x/w/flutter/dev/bots/suite_runners/run_verify_binaries_codesigned_tests.dart:28:3)
� <asynchronous suspension>
� #2      _runFromList (file:///Volumes/Work/s/w/ir/x/w/flutter/dev/bots/utils.dart:601:5)
� <asynchronous suspension>
� #3      main (file:///Volumes/Work/s/w/ir/x/w/flutter/dev/bots/test.dart:125:5)
� <asynchronous suspension>
� 
� The test.dart script should be corrected to catch this error and call foundError().
� Some tests are likely to have been skipped.
��������������������������������������������������������������������������������
```

I've updated the tests to include the listed artifact.  

### Open questions
1. Is it possible that the test failed only on the first binary?
2. Do we expect a need to add the remainder of the [entitlement changes](flutter/engine@c9b9d57)?
3. I am under the assumption that the bots pull from master and are not branch specific, is this a correct assumption?

CC @christopherfujino @cbracken

The crash indicates that FlutterJNI is returning a nullptr
SurfaceControl.Transaction. That likely indicates that we're trying to
rasterize a frame before the platform view controller is setup.
Potentially a startup race?

At any rate, if the PVC is null that means there is no platform views -
so it should be safe to create a tx on the fly. Interestingly I cannot
repro this locally even on the same device.

```
[2025-02-11 21:50:37.462356] [STDOUT] stdout: [ +173 ms] *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
[2025-02-11 21:50:37.462539] [STDOUT] stdout: [        ] Build fingerprint: 'google/cheetah/cheetah:13/TQ3A.230901.001/10750268:user/release-keys'
[2025-02-11 21:50:37.462564] [STDOUT] stdout: [        ] Revision: 'MP1.0'
[2025-02-11 21:50:37.463914] [STDOUT] stdout: [   +1 ms] ABI: 'arm64'
[2025-02-11 21:50:37.463946] [STDOUT] stdout: [        ] Timestamp: 2025-02-11 21:57:42.183302140-0800
[2025-02-11 21:50:37.463959] [STDOUT] stdout: [        ] Process uptime: 3s
[2025-02-11 21:50:37.464054] [STDOUT] stdout: [        ] Cmdline: dev.benchmarks.platform_views_layout
[2025-02-11 21:50:37.464174] [STDOUT] stdout: [        ] pid: 15185, tid: 15246, name: 1.raster  >>> dev.benchmarks.platform_views_layout <<<
[2025-02-11 21:50:37.464354] [STDOUT] stdout: [        ] uid: 10250
[2025-02-11 21:50:37.464398] [STDOUT] stdout: [        ] tagged_addr_ctrl: 0000000000000001 (PR_TAGGED_ADDR_ENABLE)
[2025-02-11 21:50:37.464440] [STDOUT] stdout: [        ] signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0000000000000000
[2025-02-11 21:50:37.464602] [STDOUT] stdout: [        ] Cause: null pointer dereference
[2025-02-11 21:50:37.464651] [STDOUT] stdout: [        ]     x0  b400007b82ff2e70  x1  000000000000002d  x2  b400007c3309f370  x3  0000007abbcc6a23
[2025-02-11 21:50:37.464745] [STDOUT] stdout: [        ]     x4  0000007a30d286b0  x5  0000007a4f6dd47b  x6  0000000000000000  x7  61686b4b11ff3a78
[2025-02-11 21:50:37.464831] [STDOUT] stdout: [        ]     x8  0000000000000000  x9  1417c2bd490e1f78  x10 0000000000000010  x11 000000000000009c
[2025-02-11 21:50:37.464933] [STDOUT] stdout: [        ]     x12 0000000000000adb  x13 b400007ba2fe9510  x14 0000000000000e6b  x15 b400007ba2fe9510
[2025-02-11 21:50:37.465012] [STDOUT] stdout: [        ]     x16 0000000000000001  x17 0000000000000067  x18 0000007a2f996000  x19 b400007b82ff2e70
[2025-02-11 21:50:37.465082] [STDOUT] stdout: [        ]     x20 000000000000002d  x21 b400007ae3064b60  x22 b400007af30d0fa8  x23 0000000000000001
[2025-02-11 21:50:37.465155] [STDOUT] stdout: [        ]     x24 0000007a30d2a000  x25 b400007b73028fb0  x26 0000007a3a22da20  x27 000000003b9bf6c8
[2025-02-11 21:50:37.465235] [STDOUT] stdout: [        ]     x28 b400007af30d0fa8  x29 b400007ad3022cd0
[2025-02-11 21:50:37.465318] [STDOUT] stdout: [        ]     lr  0000007a3a8c7918  sp  0000007a30d28940  pc  0000000000000000  pst 0000000040001000
[2025-02-11 21:50:37.465401] [STDOUT] stdout: [        ] backtrace:
[2025-02-11 21:50:37.465491] [STDOUT] stdout: [        ]       #00 pc 0000000000000000  <unknown>
[2025-02-11 21:50:37.465596] [STDOUT] stdout: [        ]       #1 pc 000000000088b914  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (flutter::PlatformViewAndroidJNIImpl::createTransaction()+104) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.465688] [STDOUT] stdout: [        ]       #2 pc 000000000087f738  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (std::_fl::__function::__func<flutter::AndroidSurfaceVKImpeller::SetNativeWindow(fml::RefPtr<flutter::AndroidNativeWindow>, std::_fl::shared_ptr<flutter::PlatformViewAndroidJNI> const&)::$_0, std::_fl::allocator<flutter::AndroidSurfaceVKImpeller::SetNativeWindow(fml::RefPtr<flutter::AndroidNativeWindow>, std::_fl::shared_ptr<flutter::PlatformViewAndroidJNI> const&)::$_0>, impeller::android::SurfaceTransaction ()>::operator()()+16) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.465785] [STDOUT] stdout: [        ]       #3 pc 0000000000bdbf1c  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (std::_fl::__function::__func<impeller::AHBSwapchainImplVK::AcquireNextDrawable()::$_0, std::_fl::allocator<impeller::AHBSwapchainImplVK::AcquireNextDrawable()::$_0>, bool ()>::operator()()+1716) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.465874] [STDOUT] stdout: [        ]       flutter#4 pc 0000000000b1d180  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (flutter::SurfaceFrame::Submit()+148) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.465989] [STDOUT] stdout: [        ]       flutter#5 pc 0000000000beb2b4  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (flutter::Rasterizer::DrawToSurfacesUnsafe(flutter::FrameTimingsRecorder&, std::_fl::vector<std::_fl::unique_ptr<flutter::LayerTreeTask, std::_fl::default_delete<flutter::LayerTreeTask> >, std::_fl::allocator<std::_fl::unique_ptr<flutter::LayerTreeTask, std::_fl::default_delete<flutter::LayerTreeTask> > > >)+1284) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.466400] [STDOUT] stdout: [        ]       flutter#6 pc 0000000000beac58  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (flutter::Rasterizer::DrawToSurfaces(flutter::FrameTimingsRecorder&, std::_fl::vector<std::_fl::unique_ptr<flutter::LayerTreeTask, std::_fl::default_delete<flutter::LayerTreeTask> >, std::_fl::allocator<std::_fl::unique_ptr<flutter::LayerTreeTask, std::_fl::default_delete<flutter::LayerTreeTask> > > >)+112) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.466444] [STDOUT] stdout: [        ]       flutter#7 pc 0000000000bec144  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (std::_fl::__function::__func<flutter::Rasterizer::Draw(std::_fl::shared_ptr<flutter::Pipeline<flutter::FrameItem> > const&)::$_0, std::_fl::allocator<flutter::Rasterizer::Draw(std::_fl::shared_ptr<flutter::Pipeline<flutter::FrameItem> > const&)::$_0>, void (std::_fl::unique_ptr<flutter::FrameItem, std::_fl::default_delete<flutter::FrameItem> >)>::operator()(std::_fl::unique_ptr<flutter::FrameItem, std::_fl::default_delete<flutter::FrameItem> >&&)+192) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.466468] [STDOUT] stdout: [        ]       flutter#8 pc 0000000000bebc48  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (flutter::Rasterizer::Draw(std::_fl::shared_ptr<flutter::Pipeline<flutter::FrameItem> > const&)+360) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.466521] [STDOUT] stdout: [        ]       flutter#9 pc 0000000000bf9f7c  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (std::_fl::__function::__func<fml::internal::CopyableLambda<flutter::Shell::OnAnimatorDraw(std::_fl::shared_ptr<flutter::Pipeline<flutter::FrameItem> >)::$_0>, std::_fl::allocator<fml::internal::CopyableLambda<flutter::Shell::OnAnimatorDraw(std::_fl::shared_ptr<flutter::Pipeline<flutter::FrameItem> >)::$_0> >, void ()>::operator()()+84) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.466543] [STDOUT] stdout: [        ]       flutter#10 pc 00000000008a09ec  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (fml::MessageLoopImpl::RunExpiredTasksNow()+728) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.466667] [STDOUT] stdout: [        ]       flutter#11 pc 00000000008a4600  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (fml::MessageLoopAndroid::MessageLoopAndroid()::$_0::__invoke(int, int, void*)+84) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.466746] [STDOUT] stdout: [        ]       flutter#12 pc 0000000000011178  /system/lib64/libutils.so (android::Looper::pollOnce(int, int*, int*, void**)+808) (BuildId: 0b4a793fa8045c04066d988c68bac8bb)
[2025-02-11 21:50:37.466784] [STDOUT] stdout: [        ]       flutter#13 pc 00000000000185e4  /system/lib64/libandroid.so (ALooper_pollOnce+100) (BuildId: 682dab490c18361d5d6527bcdd86cdfa)
[2025-02-11 21:50:37.466865] [STDOUT] stdout: [        ]       flutter#14 pc 00000000008a470c  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (fml::MessageLoopAndroid::Run()+28) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.466903] [STDOUT] stdout: [        ]       flutter#15 pc 00000000008a283c  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (std::_fl::__function::__func<fml::Thread::Thread(std::_fl::function<void (fml::Thread::ThreadConfig const&)> const&, fml::Thread::ThreadConfig const&)::$_0, std::_fl::allocator<fml::Thread::Thread(std::_fl::function<void (fml::Thread::ThreadConfig const&)> const&, fml::Thread::ThreadConfig const&)::$_0>, void ()>::operator()()+116) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.466943] [STDOUT] stdout: [        ]       flutter#16 pc 00000000008a2670  /data/app/~~u9nRjz4bI1GoKFecw6gtbg==/dev.benchmarks.platform_views_layout-RoPBoOldhc38L7sINb2Vgg==/lib/arm64/libflutter.so (fml::ThreadHandle::ThreadHandle(std::_fl::function<void ()>&&)::$_0::__invoke(void*)+8) (BuildId: 8fab16f9507483301ef418db2c91ed06689696b1)
[2025-02-11 21:50:37.467002] [STDOUT] stdout: [        ]       flutter#17 pc 00000000000c226c  /apex/com.android.runtime/lib64/bionic/libc.so (__pthread_start(void*)+204) (BuildId: dc4001c2ef2dfc23467040797a96840c)
[2025-02-11 21:50:37.467058] [STDOUT] stdout: [        ]       flutter#18 pc 0000000000054a30  /apex/com.android.runtime/lib64/bionic/libc.so (__start_thread+64) (BuildId: dc4001c2ef2dfc23467040797a96840c)
[2025-02-11 21:50:37.525275] [STDOUT] stdout: [  +57 ms] 00:00 �[32m+0�[0m�[31m -1�[0m: scrolling performance test (setUpAll) �[1m�[31m[E]�[0m�[0m
```

Currently when using a `CustomScrollView`, screen readers cannot list or
move focus to elements that are outside the current Viewport and cache
extent because we do not create semantic nodes for these elements.

This change introduces `SliverEnsureSemantics` which ensures its sliver
child is included in the semantics tree, whether or not it is currently
visible on the screen or within the cache extent. This way screen
readers are aware the elements are there and can navigate to them /
create accessibility traversal menus with this information.
* Under the hood a new flag has been added to `RenderSliver` called
`ensureSemantics`. `RenderViewportBase` uses this in its
`visitChildrenForSemantics` to ensure a sliver is visited when creating
the semantics tree. Previously a sliver was not visited if it was not
visible or within the cache extent. `RenderViewportBase` also uses this
in `describeSemanticsClip` and `describeApproximatePaintClip` to ensure
a sliver child that wants to "ensure semantics" is not clipped out if it
is not currently visible in the viewport or outside the cache extent.
* `RenderSliverMultiBoxAdaptor.semanticBounds` now leverages its first
child as an anchor for assistive technologies to be able to reach it if
the Sliver is a child of `SliverEnsureSemantics`. If not it will still
be dropped from the semantics tree.
* `RenderProxySliver` now considers child overrides of `semanticBounds`.

On the engine side we move from using a joystick method to scroll with
`SemanticsAction.scrollUp` and `SemanticsAction.scrollDown` to using
`SemanticsAction.scrollToOffset` completely letting the browser drive
the scrolling with its current dom scroll position "scrollTop" or
"scrollLeft". This is possible by calculating the total quantity of
content under the scrollable and sizing the scroll element based on
that.

<details open><summary>Code sample</summary>

```dart
// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

/// Flutter code sample for [SliverEnsureSemantics].

void main() => runApp(const SliverEnsureSemanticsExampleApp());

class SliverEnsureSemanticsExampleApp extends StatelessWidget {
  const SliverEnsureSemanticsExampleApp({super.key});

  @OverRide
  Widget build(BuildContext context) {
    return const MaterialApp(home: SliverEnsureSemanticsExample());
  }
}

class SliverEnsureSemanticsExample extends StatefulWidget {
  const SliverEnsureSemanticsExample({super.key});

  @OverRide
  State<SliverEnsureSemanticsExample> createState() =>
      _SliverEnsureSemanticsExampleState();
}

class _SliverEnsureSemanticsExampleState
    extends State<SliverEnsureSemanticsExample> {
  @OverRide
  Widget build(BuildContext context) {
    final ThemeData theme = Theme.of(context);
    return Scaffold(
      appBar: AppBar(
        backgroundColor: theme.colorScheme.inversePrimary,
        title: const Text('SliverEnsureSemantics Demo'),
      ),
      body: Center(
        child: CustomScrollView(
          semanticChildCount: 106,
          slivers: <Widget>[
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 0,
                  child: Card(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: <Widget>[
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Steps to reproduce',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                          const Text('Issue description'),
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Expected Results',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Actual Results',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Code Sample',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Screenshots',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Logs',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                        ],
                      ),
                    ),
                  ),
                ),
              ),
            ),
            SliverFixedExtentList(
              itemExtent: 44.0,
              delegate: SliverChildBuilderDelegate(
                (BuildContext context, int index) {
                  return Card(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Text('Item $index'),
                    ),
                  );
                },
                childCount: 50,
                semanticIndexOffset: 1,
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 51,
                  child: Card(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Semantics(
                        header: true,
                        child: const Text('Footer 1'),
                      ),
                    ),
                  ),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 52,
                  child: Card(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Semantics(
                        header: true,
                        child: const Text('Footer 2'),
                      ),
                    ),
                  ),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 53,
                  child: Semantics(link: true, child: const Text('Link #1')),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 54,
                  child: OverflowBar(
                    children: <Widget>[
                      TextButton(
                        onPressed: () {},
                        child: const Text('Button 1'),
                      ),
                      TextButton(
                        onPressed: () {},
                        child: const Text('Button 2'),
                      ),
                    ],
                  ),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 55,
                  child: Semantics(link: true, child: const Text('Link #2')),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverSemanticsList(
                sliver: SliverFixedExtentList(
                  itemExtent: 44.0,
                  delegate: SliverChildBuilderDelegate(
                    (BuildContext context, int index) {
                      return Semantics(
                        role: SemanticsRole.listItem,
                        child: Card(
                          child: Padding(
                            padding: const EdgeInsets.all(8.0),
                            child: Text('Second List Item $index'),
                          ),
                        ),
                      );
                    },
                    childCount: 50,
                    semanticIndexOffset: 56,
                  ),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 107,
                  child: Semantics(link: true, child: const Text('Link #3')),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

// A sliver that assigns the role of SemanticsRole.list to its sliver child.
class SliverSemanticsList extends SingleChildRenderObjectWidget {
  const SliverSemanticsList({super.key, required Widget sliver})
    : super(child: sliver);

  @OverRide
  RenderSliverSemanticsList createRenderObject(BuildContext context) =>
      RenderSliverSemanticsList();
}

class RenderSliverSemanticsList extends RenderProxySliver {
  @OverRide
  void describeSemanticsConfiguration(SemanticsConfiguration config) {
    super.describeSemanticsConfiguration(config);
    config.role = SemanticsRole.list;
  }
}
```
</details>

Fixes: flutter#160217

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

---------

Co-authored-by: Renzo Olivares <[email protected]>

<!-- start_original_pr_link -->
Reverts: flutter#165589
<!-- end_original_pr_link -->
<!-- start_initiating_author -->
Initiated by: Renzo-Olivares
<!-- end_initiating_author -->
<!-- start_revert_reason -->
Reason for reverting: breaking internal tests
<!-- end_revert_reason -->
<!-- start_original_pr_author -->
Original PR Author: Renzo-Olivares
<!-- end_original_pr_author -->

<!-- start_reviewers -->
Reviewed By: {Piinks}
<!-- end_reviewers -->

<!-- start_revert_body -->
This change reverts the following previous change:
Currently when using a `CustomScrollView`, screen readers cannot list or
move focus to elements that are outside the current Viewport and cache
extent because we do not create semantic nodes for these elements.

This change introduces `SliverEnsureSemantics` which ensures its sliver
child is included in the semantics tree, whether or not it is currently
visible on the screen or within the cache extent. This way screen
readers are aware the elements are there and can navigate to them /
create accessibility traversal menus with this information.
* Under the hood a new flag has been added to `RenderSliver` called
`ensureSemantics`. `RenderViewportBase` uses this in its
`visitChildrenForSemantics` to ensure a sliver is visited when creating
the semantics tree. Previously a sliver was not visited if it was not
visible or within the cache extent. `RenderViewportBase` also uses this
in `describeSemanticsClip` and `describeApproximatePaintClip` to ensure
a sliver child that wants to "ensure semantics" is not clipped out if it
is not currently visible in the viewport or outside the cache extent.
* `RenderSliverMultiBoxAdaptor.semanticBounds` now leverages its first
child as an anchor for assistive technologies to be able to reach it if
the Sliver is a child of `SliverEnsureSemantics`. If not it will still
be dropped from the semantics tree.
* `RenderProxySliver` now considers child overrides of `semanticBounds`.

On the engine side we move from using a joystick method to scroll with
`SemanticsAction.scrollUp` and `SemanticsAction.scrollDown` to using
`SemanticsAction.scrollToOffset` completely letting the browser drive
the scrolling with its current dom scroll position "scrollTop" or
"scrollLeft". This is possible by calculating the total quantity of
content under the scrollable and sizing the scroll element based on
that.

<details open><summary>Code sample</summary>

```dart
// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

/// Flutter code sample for [SliverEnsureSemantics].

void main() => runApp(const SliverEnsureSemanticsExampleApp());

class SliverEnsureSemanticsExampleApp extends StatelessWidget {
  const SliverEnsureSemanticsExampleApp({super.key});

  @OverRide
  Widget build(BuildContext context) {
    return const MaterialApp(home: SliverEnsureSemanticsExample());
  }
}

class SliverEnsureSemanticsExample extends StatefulWidget {
  const SliverEnsureSemanticsExample({super.key});

  @OverRide
  State<SliverEnsureSemanticsExample> createState() =>
      _SliverEnsureSemanticsExampleState();
}

class _SliverEnsureSemanticsExampleState
    extends State<SliverEnsureSemanticsExample> {
  @OverRide
  Widget build(BuildContext context) {
    final ThemeData theme = Theme.of(context);
    return Scaffold(
      appBar: AppBar(
        backgroundColor: theme.colorScheme.inversePrimary,
        title: const Text('SliverEnsureSemantics Demo'),
      ),
      body: Center(
        child: CustomScrollView(
          semanticChildCount: 106,
          slivers: <Widget>[
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 0,
                  child: Card(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: <Widget>[
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Steps to reproduce',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                          const Text('Issue description'),
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Expected Results',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Actual Results',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Code Sample',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Screenshots',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                          Semantics(
                            header: true,
                            headingLevel: 3,
                            child: Text(
                              'Logs',
                              style: theme.textTheme.headlineSmall,
                            ),
                          ),
                        ],
                      ),
                    ),
                  ),
                ),
              ),
            ),
            SliverFixedExtentList(
              itemExtent: 44.0,
              delegate: SliverChildBuilderDelegate(
                (BuildContext context, int index) {
                  return Card(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Text('Item $index'),
                    ),
                  );
                },
                childCount: 50,
                semanticIndexOffset: 1,
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 51,
                  child: Card(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Semantics(
                        header: true,
                        child: const Text('Footer 1'),
                      ),
                    ),
                  ),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 52,
                  child: Card(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Semantics(
                        header: true,
                        child: const Text('Footer 2'),
                      ),
                    ),
                  ),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 53,
                  child: Semantics(link: true, child: const Text('Link #1')),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 54,
                  child: OverflowBar(
                    children: <Widget>[
                      TextButton(
                        onPressed: () {},
                        child: const Text('Button 1'),
                      ),
                      TextButton(
                        onPressed: () {},
                        child: const Text('Button 2'),
                      ),
                    ],
                  ),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 55,
                  child: Semantics(link: true, child: const Text('Link #2')),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverSemanticsList(
                sliver: SliverFixedExtentList(
                  itemExtent: 44.0,
                  delegate: SliverChildBuilderDelegate(
                    (BuildContext context, int index) {
                      return Semantics(
                        role: SemanticsRole.listItem,
                        child: Card(
                          child: Padding(
                            padding: const EdgeInsets.all(8.0),
                            child: Text('Second List Item $index'),
                          ),
                        ),
                      );
                    },
                    childCount: 50,
                    semanticIndexOffset: 56,
                  ),
                ),
              ),
            ),
            SliverEnsureSemantics(
              sliver: SliverToBoxAdapter(
                child: IndexedSemantics(
                  index: 107,
                  child: Semantics(link: true, child: const Text('Link #3')),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

// A sliver that assigns the role of SemanticsRole.list to its sliver child.
class SliverSemanticsList extends SingleChildRenderObjectWidget {
  const SliverSemanticsList({super.key, required Widget sliver})
    : super(child: sliver);

  @OverRide
  RenderSliverSemanticsList createRenderObject(BuildContext context) =>
      RenderSliverSemanticsList();
}

class RenderSliverSemanticsList extends RenderProxySliver {
  @OverRide
  void describeSemanticsConfiguration(SemanticsConfiguration config) {
    super.describeSemanticsConfiguration(config);
    config.role = SemanticsRole.list;
  }
}
```
</details>

Fixes: flutter#160217

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.
<!-- end_revert_body -->

Co-authored-by: auto-submit[bot] <[email protected]>

Fixes error found in rolling to google.

```
[☠] Android toolchain - develop for Android devices (the doctor check crashed)
    ✗ Due to an error, the doctor check did not complete. If the error message
      below is not helpful, please let us know about this issue at
      https://github.com/flutter/flutter/issues.
    ✗ type 'Null' is not a subtype of type 'String' of 'executable'
    • #0      LocalProcessManager.canRun
      (package:process/src/interface/local_process_manager.dart:124)
      #1      getEmulatorVersion
      (package:flutter_tools/src/android/android_workflow.dart:64)
      #2      AndroidValidator.validateImpl
      (package:flutter_tools/src/android/android_workflow.dart:200)
      #3      DoctorValidator.validate
      (package:flutter_tools/src/doctor_validator.dart:58)
      flutter#4      Doctor.startValidatorTasks.<anonymous closure>
      (package:flutter_tools/src/doctor.dart:244)
      flutter#5      asyncGuard.<anonymous closure>
      (package:flutter_tools/src/base/async_guard.dart:109)
      flutter#6      _rootRun (dart:async/zone.dart:1525)
      flutter#7      _CustomZone.run (dart:async/zone.dart:1422)
      flutter#8      _runZoned (dart:async/zone.dart:2033)
      flutter#9      runZonedGuarded (dart:async/zone.dart:2019)
      flutter#10     runZoned (dart:async/zone.dart:1952)
      flutter#11     asyncGuard (package:flutter_tools/src/base/async_guard.dart:106)
      flutter#12     Doctor.startValidatorTasks
      (package:flutter_tools/src/doctor.dart:234)
      flutter#13     Doctor.diagnose (package:flutter_tools/src/doctor.dart:372)
      flutter#14     DoctorCommand.runCommand
      (package:flutter_tools/src/commands/doctor.dart:59)
      flutter#15     FlutterCommand.verifyThenRunCommand
      (package:flutter_tools/src/runner/flutter_command.dart:1897)
      <asynchronous suspension>
      flutter#16     FlutterCommand.run.<anonymous closure>
      (package:flutter_tools/src/runner/flutter_command.dart:1551)
      <asynchronous suspension>
      flutter#17     AppContext.run.<anonymous closure>
      (package:flutter_tools/src/base/context.dart:154)
      <asynchronous suspension>
      flutter#18     CommandRunner.runCommand (package:args/command_runner.dart:212)
      <asynchronous suspension>
      flutter#19     FlutterCommandRunner.runCommand.<anonymous closure>
      (package:flutter_tools/src/runner/flutter_command_runner.dart:501)
      <asynchronous suspension>
      flutter#20     AppContext.run.<anonymous closure>
      (package:flutter_tools/src/base/context.dart:154)
      <asynchronous suspension>
      flutter#21     FlutterCommandRunner.runCommand
      (package:flutter_tools/src/runner/flutter_command_runner.dart:438)
      <asynchronous suspension>
      flutter#22     run.<anonymous closure>.<anonymous closure>
      (package:flutter_tools/runner.dart:98)
      <asynchronous suspension>
      flutter#23     AppContext.run.<anonymous closure>
      (package:flutter_tools/src/base/context.dart:154)
      <asynchronous suspension>
      flutter#24     AppContext.run.<anonymous closure>
      (package:flutter_tools/src/base/context.dart:154)
      <asynchronous suspension>
      flutter#25     run (package:mobile.flutter.cli/flutter_tools.dart:106)
      <asynchronous suspension>
      flutter#26     main (google3:///mobile/flutter/cli/bin/cli_usage_aot.dart:4)
```

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

This test passes when run locally as instructed in the README for the
devicelab
```
../../bin/cache/dart-sdk/bin/dart bin/test_runner.dart test -t android_verified_input_test
```

but fails on CI:

https://ci.chromium.org/ui/p/flutter/builders/staging/Linux_pixel_7pro%20android_verified_input_test/106/overview
```
[2025-11-03 11:08:04.090018] [STDOUT] stdout: [        ]   Original error: ext.flutter.driver: (-32000) Service connection disposed
[2025-11-03 11:08:04.090156] [STDOUT] stdout: [        ]   Original stack trace:
[2025-11-03 11:08:04.090199] [STDOUT] stdout: [        ]   #0      new _OutstandingRequest (package:vm_service/src/vm_service.dart:268:34)
[2025-11-03 11:08:04.091572] [STDOUT] stdout: [        ]   #1      VmService._call.<anonymous closure> (package:vm_service/src/vm_service.dart:1950:25)
[2025-11-03 11:08:04.091647] [STDOUT] stdout: [        ]   #2      VmService._call (package:vm_service/src/vm_service.dart:1962:8)
[2025-11-03 11:08:04.091674] [STDOUT] stdout: [        ]   #3      VmService.callServiceExtension (package:vm_service/src/vm_service.dart:1901:14)
[2025-11-03 11:08:04.091693] [STDOUT] stdout: [        ]   flutter#4      VMServiceFlutterDriver.sendCommand (package:flutter_driver/src/driver/vmservice_driver.dart:327:12)
[2025-11-03 11:08:04.091713] [STDOUT] stdout: [        ]   flutter#5      FlutterDriver.requestData (package:flutter_driver/src/driver/driver.dart:573:13)
[2025-11-03 11:08:04.091733] [STDOUT] stdout: [        ]   flutter#6      main.<anonymous closure> (file:///opt/s/w/ir/x/w/rc/tmpv6pcbna2/flutter%20sdk/dev/integration_tests/android_verified_input/test_driver/main_test.dart:28:57)
[2025-11-03 11:08:04.091750] [STDOUT] stdout: [        ]   <asynchronous suspension>
[2025-11-03 11:08:04.091767] [STDOUT] stdout: [        ]   flutter#7      Declarer.test.<anonymous closure>.<anonymous closure> (package:test_api/src/backend/declarer.dart:242:9)
[2025-11-03 11:08:04.091784] [STDOUT] stdout: [        ]   <asynchronous suspension>
[2025-11-03 11:08:04.092408] [STDOUT] stdout: [        ]   flutter#8      Declarer.test.<anonymous closure> (package:test_api/src/backend/declarer.dart:240:7)
[2025-11-03 11:08:04.092472] [STDOUT] stdout: [        ]   <asynchronous suspension>
[2025-11-03 11:08:04.092502] [STDOUT] stdout: [        ]   flutter#9      Invoker._waitForOutstandingCallbacks.<anonymous closure> (package:test_api/src/backend/invoker.dart:282:9)
```

Try copying this configuration used by other tests as a speculative fix.
I can't get this test to kick off in presubmit, so I suppose we will
just try this. The test is marked bringup anyways so it won't block the
tree if this doesn't help.

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

**Note**: The Flutter team is currently trialing the use of [Gemini Code
Assist for
GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code).
Comments from the `gemini-code-assist` bot should not be taken as
authoritative feedback from the Flutter team. If you find its comments
useful you can update your code accordingly, but if you are unsure or
disagree with the feedback, please feel free to wait for a Flutter team
member's review for guidance on which automated comments should be
addressed.

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

---------

Co-authored-by: Gray Mackall <[email protected]>

Instead of using fake touch events. 

Before this patch `FlutterViewController` sends two fake touch events
(down and up), at `(0, 0)` to the framework to signal that the status
bar is tapped on iOS. The scaffold widget and the cupertino page
scaffold widget set up gesture detectors to listen for these fake taps,
and scroll the "primary" scrollable container to the top in response.

This messaging mechanism is sometimes ambiguous, as the framework may
interpret that as a pair of regular pointer tap events (for instance in
flutter#177992 the modal barrier claims the tap gesture and as a result the
modal barrier is dismissed by the fake touch events). This PR changes
that to communicate the status bar tap event via a new system channel,
and dispatch the events via `WidgetsBindingObserver`s in the framework.

See also
flutter#177992 (comment)

Fixes flutter#177992, fixes flutter#175606

It appears that UIKit also has access to the coordinates of the touch
events to determine which scrollable view(s?) to dispatch the scroll to
top event to.
```objc
  * frame #0: 0x00000001032f6520 UIPlayground.debug.dylib`MyScrollViewController.scrollViewShouldScrollToTop(scrollView=0x0000000106014800) at UIScrollView.swift:13:3
    frame #2: 0x00000001867c9300 UIKitCore`-[UIScrollView _scrollToTopIfPossible:] + 316
    frame #3: 0x00000001867c9604 UIKitCore`-[UIScrollView _scrollToTopFromTouchAtScreenLocation:resultHandler:] + 40
    frame flutter#4: 0x0000000186299bbc UIKitCore`__71-[UIWindow _scrollToTopViewsUnderScreenPointIfNecessary:resultHandler:]_block_invoke.358 + 168
    frame flutter#5: 0x000000018629981c UIKitCore`-[UIWindow _scrollToTopViewsUnderScreenPointIfNecessary:resultHandler:] + 1212
    frame flutter#6: 0x000000018581ed8c UIKitCore`-[UIStatusBarManager _handleScrollToTopAtXPosition:] + 192
    frame flutter#7: 0x000000018581eb60 UIKitCore`-[UIStatusBarManager handleTapAction:] + 60
```
Unfortunately that information is not available to user application. The
iOS accessibility bridge currently does create dummy UIScrollViews for
each scrollable in the accessibility tree so may be we can take
advantage of that in the future.

## Pre-launch Checklist

- [ ] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [ ] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [ ] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [ ] I signed the [CLA].
- [ ] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [ ] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [ ] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [ ] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

**Note**: The Flutter team is currently trialing the use of [Gemini Code
Assist for
GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code).
Comments from the `gemini-code-assist` bot should not be taken as
authoritative feedback from the Flutter team. If you find its comments
useful you can update your code accordingly, but if you are unsure or
disagree with the feedback, please feel free to wait for a Flutter team
member's review for guidance on which automated comments should be
addressed.

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md