Enable private field promotion for framework

[goderbauer]

New feature in upcoming Dart 3.2. See dart-lang/language#2020. Feature is enabled by bumping the min SDK version to 3.2.

Part of #134476.

[goderbauer]

The web compiler is unhappy about the removal of ! here and below:

/b/s/w/ir/x/w/flutter/bin/cache/dart-sdk/bin/dart --disable-dart-dev /b/s/w/ir/x/w/flutter/bin/cache/dart-sdk/bin/snapshots/frontend_server.dart.snapshot --sdk-root /b/s/w/ir/x/w/flutter/bin/cache/flutter_web_sdk/ --incremental --target=dartdevc --experimental-emit-debug-metadata -DDART_HHH_BOT=false -DFLUTTER_WEB_AUTO_DETECT=false -DFLUTTER_WEB_USE_SKIA=true --output-dill /b/s/w/ir/x/t/flutter_tools.VOZITK/flutter_test.PPUCHG/out --packages /b/s/w/ir/x/w/flutter/packages/flutter/.dart_tool/package_config.json -Ddart.vm.profile=false -Ddart.vm.product=false --enable-asserts --track-widget-creation --filesystem-root /b/s/w/ir/x/w/flutter/packages/flutter/test --filesystem-root /b/s/w/ir/x/t/flutter_tools.VOZITK/flutter_test.PPUCHG/ --filesystem-scheme org-dartlang-app --initialize-from-dill build/a2632b1a2d119a1f9ce340959afb28ff.cache.dill.track.dill --platform file:///b/s/w/ir/x/w/flutter/bin/cache/flutter_web_sdk/kernel/ddc_outline_sound.dill --verbosity=error --sound-null-safety
[  +16 ms] <- compile org-dartlang-app:///main.dart
[+11509 ms] lib/src/rendering/error.dart:160:20: Error: Method 'layout' cannot be called on 'Paragraph?' because it is potentially null.
[   +2 ms]  - 'Paragraph' is from 'dart:ui'.
[        ] Try calling using ?. instead.
[        ]         _paragraph.layout(ui.ParagraphConstraints(width: width));
[        ]                    ^^^^^^
[   +6 ms] lib/src/rendering/error.dart:161:52: Error: Property 'height' cannot be accessed on 'Paragraph?' because it is potentially null.
[        ]  - 'Paragraph' is from 'dart:ui'.
[        ] Try accessing using ?. instead.
[        ]         if (size.height > padding.top + _paragraph.height + padding.bottom) {
[        ]                                                    ^^^^^^
[        ] lib/src/rendering/error.dart:61:28: Context: '_paragraph' refers to a property so it couldn't be promoted.
[        ] See http://dart.dev/go/non-promo-property
[        ]   late final ui.Paragraph? _paragraph;
[        ]                            ^
[   +1 ms] lib/src/rendering/error.dart:164:38: Error: The argument type 'Paragraph?' can't be assigned to the parameter type 'Paragraph' because 'Paragraph?' is nullable and 'Paragraph' isn't.
[        ]  - 'Paragraph' is from 'dart:ui'.
[        ]         context.canvas.drawParagraph(_paragraph, offset + Offset(left, top));

(from https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8770206943273787297/+/u/run_test.dart_for_web_canvaskit_tests_shard_and_subshard_0/test_stdout)

[goderbauer]

The ! should be removable because of if (_paragraph != null) in line 152, though. This issue also only surfaces on the web. When running in the VM, the removal of the ! is not causing any trouble. Presumably, there is a bug somewhere in the web compilation pipeline?

@stereotype441 Any idea what may be going on here? If necessary, I can try to boil this down to a smaller repro case.

[goderbauer]

We likely have to wait for dart-lang/sdk@1da590f to roll into Flutter, which is expected to fix this problem.

[goderbauer]

Fix rolled in with #134763.

[gspencergoog]

[auto-submit]

auto label is removed for flutter/flutter/134473, due to - The status or check suite Google testing has failed. Please fix the issues identified (or deflake) before re-applying this label.

[auto-submit]

auto label is removed for flutter/flutter/134473, due to - The status or check suite Linux web_tests_2 has failed. Please fix the issues identified (or deflake) before re-applying this label.

• The status or check suite Linux web_tests_1 has failed. Please fix the issues identified (or deflake) before re-applying this label.