tree f39d3d76a8c4af68d88afec5d3a51b52f920d729
parent fe8912ec3e89b17f754dcbc27528801ca2ef0af4
author Yegor <yjbanov@google.com> 1683694942 -0700
committer dart-internal-monorepo <dart-internal-monorepo@dart-ci-internal.iam.gserviceaccount.com> 1683695441 -0700

[web] dialog a11y fixes (#41681)

Fixes two issues in dialog accessibility:

* Fixes https://github.com/flutter/flutter/issues/45207 by setting `role="dialog"` on nodes that have both `scopesRoute` and `namesRoute` set. There's no guarantee that this combination of flags is an actual dialog, but it's close enough, and it makes the screen reader announce the appearance of the dialog. Note that `scopesRoute` alone is not sufficient, because Flutter uses it for overlays that are not semantically dialogs, such as dismiss barriers.
* Fixes an issue with focus management, where focus fails to transfer to background content after the dialog is dismissed. This happened because `EngineSemanticsOwner._semanticsTree` retained descendants of parents that were removed. This is benign in many cases. However, for focus this is problematic because the HTML element can go away and come back (losing focus along the way), but its corresponding `SemanticsObject` is never marked as "dirty" and fails to update and request focus.

I'm hoping this is sufficient to fix b/251839784 as well. Will work with the relevant team to find out.
https://dart.googlesource.com/external/github.com/flutter/engine/+/9504b30070fd251c125c98880677c72ff6dbec05