Unreverts #54902 with fixes for a failing integration test.

Avoid calling `builder` in `ConstrainedLayoutBuilder` when layout constraints are the same.

[Design doc](flutter.dev/go/layout-builder-optimization).

## Related Issues

Fixes https://github.com/flutter/flutter/issues/6469

* [flutter_tools] integration l10n tool

* add runtime skip to build system

* Update build_system.dart

* add links to issues, comments

* Update packages/flutter_tools/test/general.shard/build_system/build_system_test.dart
Co-authored-by: Shi-Hao Hong <shihaohong@google.com>

* Update packages/flutter_tools/lib/src/build_system/targets/localizations.dart
Co-authored-by: Shi-Hao Hong <shihaohong@google.com>

* Update localizations.dart

* switch to gen_l10n localizations

* fix tests
Co-authored-by: Shi-Hao Hong <shihaohong@google.com>

This engine version contains the Dart SDK that has been unforked for the
null-safety feature.

9b905d3f0 Manual roll of Dart 617bc54b71...39e0e75fcf (#18215)

Enable tree-shake-icons by default for non-web targets. Make missing fonts a status print

7e205b37e Roll src/fuchsia/sdk/mac from 1MVsE... to 4MCVP... (#18217)
9193d8ff8 Roll src/third_party/skia 0dc207f836da..a14084ba1b41 (3 commits) (#18219)
403931ff2 Add FlValue (#18185)
46a6d966a [SkParagraph] Copy text height behavior to the Skia paragraph style (#18178)
e7ee47d91 [web] Implement matrix parameter for linear gradient (#18208)
28d99854a Reland again "Remove layer integral offset snapping #17112" (#18160)
5e361f57d Roll src/third_party/skia c66cd987f7c0..0dc207f836da (5 commits) (#18212)
716dbf00c Refactor GLFW embedding to support headless mode (#18205)
23cca3211 Manual Roll of Dart 39e0e75fcf...ce62ad2e8b (#18211)
15f72b8c0 Support EventChannel C++ plugin API for Linux/Windows (#17015)
e5a7ca577 Handle leak of message handle when no engine present (#18157)
d3bde19c1 add docs to platformviewios (and some drive-by changes) (#17593)
b582d774f Roll src/third_party/skia 0066adefa97d..c66cd987f7c0 (4 commits) (#18206)
5e7d6d05f Roll src/third_party/skia edea19858ccc..0066adefa97d (3 commits) (#18203)
88b9d4240 Remove the global engine entry timestamp (#18182)
0dffdd5de Roll src/third_party/dart e86e4d61834a..ce62ad2e8b40 (13 commits) (#18201)
56fe6d255 Roll src/third_party/skia 2871ab0727bf..edea19858ccc (3 commits) (#18198)
bcdf99121 Fixed ChildSceneLayer elevation issue on Fuchsia. (#18144)
ede658e2d [profiling] CPU Profiling support for iOS (#18087)
d043923d7 Roll src/third_party/skia e3d1de7c5281..2871ab0727bf (1 commits) (#18197)
807f1914e Roll src/third_party/dart 733153eb517c..e86e4d61834a (6 commits) (#18195)
fe3f8df81 Roll src/third_party/skia 3b2db26c59d6..e3d1de7c5281 (4 commits) (#18192)
34b062998 Roll fuchsia/sdk/core/mac-amd64 from jMJqf... to 1MVsE... (#18194)
e9b2afefd Roll fuchsia/sdk/core/linux-amd64 from RpHTv... to MhpFP... (#18191)
35fa00629 Roll src/third_party/skia 88d04cb51acf..3b2db26c59d6 (1 commits) (#18190)
e54bb9e20 Roll src/third_party/dart 4da5b40fb6dc..733153eb517c (23 commits) (#18188)

`assert(app is IOSApp)` fails if `app` is null, and `app` is an
optional argument. `app` is passed to `_IOSSimulatorLogReader`, which
already handles it being null.

Workaround for cached web builds with --[no-]track-widget-creation flags.
Similar PR: #23299

This reverts commit 053c3881.