Revert "[web] Move text editing nodes outside of shadowDOM" (#40847)

Reverts flutter/engine#39688

Looks like this is causing the roll to the framework to fail. See
https://ci.chromium.org/ui/p/flutter/builders/try/Linux%20web_long_running_tests_4_5/34083/overview

```
00:03 +1 -1: Hello World App enable accessibility [E]

  JavaScriptException (500): javascript error: Cannot read properties of null (reading 'querySelector')
    (Session info: headless chrome=96.0.4664.0)

  package:webdriver/src/handler/w3c/utils.dart 57:9       parseW3cResponse
  package:webdriver/src/handler/w3c/core.dart 59:19       W3cCoreHandler.parseExecuteResponse
  package:webdriver/src/async/web_driver.dart 260:37      WebDriver.execute.<fn>
  package:webdriver/src/common/request_client.dart 96:32  AsyncRequestClient.send
  ===== asynchronous gap ===========================
  test_driver/smoke_web_engine_test.dart 41:40            main.<fn>.<fn>
  ===== asynchronous gap ===========================
  package:test_api/src/backend/declarer.dart 215:9        Declarer.test.<fn>.<fn>
  ===== asynchronous gap ===========================
  package:test_api/src/backend/declarer.dart 213:7        Declarer.test.<fn>
  ===== asynchronous gap ===========================
  package:test_api/src/backend/invoker.dart 258:9         Invoker._waitForOutstandingCallbacks.<fn>


00:03 +1 -1: Hello World App (tearDownAll)

```
12 files changed
tree: 99e9143c33dfc46c8ce68c9d4d0a7bd731c55e3c
  1. .github/
  2. assets/
  3. benchmarking/
  4. build/
  5. ci/
  6. common/
  7. display_list/
  8. docs/
  9. examples/
  10. flow/
  11. flutter_frontend_server/
  12. flutter_vma/
  13. fml/
  14. impeller/
  15. lib/
  16. runtime/
  17. shell/
  18. sky/
  19. testing/
  20. third_party/
  21. tools/
  22. vulkan/
  23. wasm/
  24. web_sdk/
  25. .ci.yaml
  26. .clang-format
  27. .clang-tidy
  28. .gitattributes
  29. .gitignore
  30. .pylintrc
  31. .style.yapf
  32. analysis_options.yaml
  33. AUTHORS
  34. BUILD.gn
  35. CODEOWNERS
  36. CONTRIBUTING.md
  37. DEPS
  38. Doxyfile
  39. LICENSE
  40. README.md
README.md

Flutter Engine

OpenSSF Scorecard

Flutter is Google's SDK for crafting beautiful, fast user experiences for mobile, web, and desktop from a single codebase. Flutter works with existing code, is used by developers and organizations around the world, and is free and open source.

The Flutter Engine is a portable runtime for hosting Flutter applications. It implements Flutter's core libraries, including animation and graphics, file and network I/O, accessibility support, plugin architecture, and a Dart runtime and compile toolchain. Most developers will interact with Flutter via the Flutter Framework, which provides a modern, reactive framework, and a rich set of platform, layout and foundation widgets.

If you want to run/contribute to Flutter Web engine, more tooling can be found at felt. This is a tool written to make web engine development experience easy.

If you are new to Flutter, then you will find more general information on the Flutter project, including tutorials and samples, on our Web site at Flutter.dev. For specific information about Flutter's APIs, consider our API reference which can be found at the docs.flutter.dev.

Flutter is a fully open source project, and we welcome contributions. Information on how to get started can be found at our contributor guide.