Bump min Dart SDK to 3.9, reformat

[kevmoo]

No description provided.

[gemini-code-assist]

Code Review

This pull request bumps the minimum Dart SDK version to ^3.9.0 and applies the corresponding code formatting changes across the package. The SDK version update is correctly reflected in pubspec.yaml and CHANGELOG.md. A new lint rule, remove_deprecations_in_breaking_versions, has also been added to analysis_options.yaml. The numerous formatting changes are consistent with the latest dart format style, improving code readability and maintainability. The changes are correct and well-executed. This PR is good to merge.

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:bazel_worker	1.1.4	already published at pub.dev
package:benchmark_harness	2.4.0-wip	WIP (no publish necessary)
package:boolean_selector	2.1.2	already published at pub.dev
package:browser_launcher	1.1.3	already published at pub.dev
package:cli_config	0.2.1-wip	WIP (no publish necessary)
package:cli_util	0.5.0-wip	WIP (no publish necessary)
package:clock	1.1.3-wip	WIP (no publish necessary)
package:code_builder	4.11.1-wip	WIP (no publish necessary)
package:coverage	1.15.0	already published at pub.dev
package:csslib	1.0.2	already published at pub.dev
package:extension_discovery	2.1.0	already published at pub.dev
package:file	7.0.2-wip	WIP (no publish necessary)
package:file_testing	3.1.0-wip	WIP (no publish necessary)
package:glob	2.1.3	already published at pub.dev
package:graphs	2.3.3-wip	WIP (no publish necessary)
package:html	0.15.7-wip	WIP (no publish necessary)
package:io	1.1.0-wip	WIP (no publish necessary)
package:json_rpc_2	4.0.0	already published at pub.dev
package:markdown	7.3.1-wip	WIP (no publish necessary)
package:mime	2.1.0-wip	WIP (no publish necessary)
package:oauth2	2.0.5	already published at pub.dev
package:package_config	2.3.0-wip	WIP (no publish necessary)
package:pool	1.5.2	already published at pub.dev
package:process	5.0.5	already published at pub.dev
package:pub_semver	2.2.0	already published at pub.dev
package:pubspec_parse	1.5.1-wip	WIP (no publish necessary)
package:source_map_stack_trace	2.1.3-wip	WIP (no publish necessary)
package:source_maps	0.10.14-wip	WIP (no publish necessary)
package:source_span	1.10.1	already published at pub.dev
package:sse	4.1.8	already published at pub.dev
package:stack_trace	1.12.2-wip	(error) pubspec version (1.12.2-wip) and changelog (1.12.2-dev) don't agree
package:stream_channel	2.1.4	already published at pub.dev
package:stream_transform	2.1.2-wip	WIP (no publish necessary)
package:string_scanner	1.4.1	already published at pub.dev
package:term_glyph	1.2.3-wip	WIP (no publish necessary)
package:test_reflective_loader	0.5.0	ready to publish	test_reflective_loader-v0.5.0
package:timing	1.0.2	already published at pub.dev
package:unified_analytics	8.0.8	ready to publish	unified_analytics-v8.0.8
package:watcher	1.1.5-wip	WIP (no publish necessary)
package:yaml	3.1.3	already published at pub.dev
package:yaml_edit	2.2.2	already published at pub.dev

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

[coveralls]

Pull Request Test Coverage Report for Build 19520577800

Details

• 130 of 140 (92.86%) changed or added relevant lines in 30 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.2%) to 95.976%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkgs/markdown/lib/src/inline_parser.dart	24	26	92.31%
pkgs/markdown/lib/src/inline_syntaxes/delimiter_syntax.dart	4	6	66.67%
pkgs/markdown/lib/src/inline_syntaxes/color_swatch_syntax.dart	0	6	0.0%

Files with Coverage Reduction	New Missed Lines	%
pkgs/markdown/lib/src/inline_syntaxes/delimiter_syntax.dart	1	87.8%

Totals
Change from base Build 19516894004:	-0.2%
Covered Lines:	1574
Relevant Lines:	1640

---

💛 - Coveralls

[github-actions]

PR Health

License Headers ✔️

// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

Files
no missing headers

All source files should start with a license header.

Unrelated files missing license headers

Files
pkgs/bazel_worker/benchmark/benchmark.dart
pkgs/benchmark_harness/integration_test/perf_benchmark_test.dart
pkgs/boolean_selector/example/example.dart
pkgs/clock/lib/clock.dart
pkgs/clock/lib/src/clock.dart
pkgs/clock/lib/src/default.dart
pkgs/clock/lib/src/stopwatch.dart
pkgs/clock/lib/src/utils.dart
pkgs/clock/test/clock_test.dart
pkgs/clock/test/default_test.dart
pkgs/clock/test/stopwatch_test.dart
pkgs/clock/test/utils.dart
pkgs/coverage/lib/src/coverage_options.dart
pkgs/html/example/main.dart
pkgs/html/lib/dom.dart
pkgs/html/lib/dom_parsing.dart
pkgs/html/lib/html_escape.dart
pkgs/html/lib/parser.dart
pkgs/html/lib/src/constants.dart
pkgs/html/lib/src/encoding_parser.dart
pkgs/html/lib/src/html_input_stream.dart
pkgs/html/lib/src/list_proxy.dart
pkgs/html/lib/src/query_selector.dart
pkgs/html/lib/src/token.dart
pkgs/html/lib/src/tokenizer.dart
pkgs/html/lib/src/treebuilder.dart
pkgs/html/lib/src/utils.dart
pkgs/html/test/dom_test.dart
pkgs/html/test/parser_feature_test.dart
pkgs/html/test/parser_test.dart
pkgs/html/test/query_selector_test.dart
pkgs/html/test/selectors/level1_baseline_test.dart
pkgs/html/test/selectors/level1_lib.dart
pkgs/html/test/selectors/selectors.dart
pkgs/html/test/support.dart
pkgs/html/test/tokenizer_test.dart
pkgs/html/test/trie_test.dart
pkgs/html/tool/generate_trie.dart
pkgs/pubspec_parse/test/git_uri_test.dart
pkgs/stack_trace/example/example.dart
pkgs/watcher/test/custom_watcher_factory_test.dart
pkgs/yaml_edit/example/example.dart

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API leaks ✔️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbol	Leaking sources

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Breaking changes ⚠️

Package	Change	Current Version	New Version	Needed Version	Looking good?
markdown	Non-Breaking	7.3.0	7.3.1-wip	7.4.0 Got "7.3.1-wip" expected >= "7.4.0" (non-breaking changes)	⚠️

This check can be disabled by tagging the PR with skip-breaking-check.

Coverage ⚠️

File	Coverage
pkgs/markdown/example/app.dart	💔 Not covered
pkgs/markdown/lib/src/assets/case_folding.dart	💔 Not covered
pkgs/markdown/lib/src/assets/html_entities.dart	💔 Not covered
pkgs/markdown/lib/src/ast.dart	💚 100 %
pkgs/markdown/lib/src/block_parser.dart	💚 91 %
pkgs/markdown/lib/src/block_syntaxes/alert_block_syntax.dart	💚 87 % ⬆️ 2 %
pkgs/markdown/lib/src/block_syntaxes/block_syntax.dart	💚 76 % ⬆️ 3 %
pkgs/markdown/lib/src/block_syntaxes/blockquote_syntax.dart	💚 100 %
pkgs/markdown/lib/src/block_syntaxes/code_block_syntax.dart	💚 100 %
pkgs/markdown/lib/src/block_syntaxes/fenced_code_block_syntax.dart	💚 98 %
pkgs/markdown/lib/src/block_syntaxes/footnote_def_syntax.dart	💚 100 %
pkgs/markdown/lib/src/block_syntaxes/link_reference_definition_syntax.dart	💚 100 %
pkgs/markdown/lib/src/block_syntaxes/list_syntax.dart	💚 94 %
pkgs/markdown/lib/src/block_syntaxes/table_syntax.dart	💚 90 %
pkgs/markdown/lib/src/document.dart	💚 95 %
pkgs/markdown/lib/src/extension_set.dart	💔 95 % ⬇️ 1 %
pkgs/markdown/lib/src/html_renderer.dart	💚 100 %
pkgs/markdown/lib/src/inline_parser.dart	💚 98 % ⬆️ 0 %
pkgs/markdown/lib/src/inline_syntaxes/autolink_extension_syntax.dart	💚 98 %
pkgs/markdown/lib/src/inline_syntaxes/autolink_syntax.dart	💚 100 %
pkgs/markdown/lib/src/inline_syntaxes/color_swatch_syntax.dart	💔 27 % ⬇️ 13 %
pkgs/markdown/lib/src/inline_syntaxes/decode_html_syntax.dart	💚 100 %
pkgs/markdown/lib/src/inline_syntaxes/delimiter_syntax.dart	💔 88 % ⬇️ 2 %
pkgs/markdown/lib/src/inline_syntaxes/emphasis_syntax.dart	💚 100 %
pkgs/markdown/lib/src/inline_syntaxes/escape_syntax.dart	💚 100 %
pkgs/markdown/lib/src/inline_syntaxes/footnote_ref_syntax.dart	💚 100 %
pkgs/markdown/lib/src/inline_syntaxes/image_syntax.dart	💚 100 %
pkgs/markdown/lib/src/inline_syntaxes/inline_html_syntax.dart	💚 100 %
pkgs/markdown/lib/src/inline_syntaxes/inline_syntax.dart	💚 100 %
pkgs/markdown/lib/src/inline_syntaxes/link_syntax.dart	💚 99 %
pkgs/markdown/lib/src/inline_syntaxes/strikethrough_syntax.dart	💚 100 %
pkgs/markdown/lib/src/line.dart	💚 100 %
pkgs/markdown/lib/src/patterns.dart	💚 100 %
pkgs/markdown/lib/src/util.dart	💚 100 %
pkgs/markdown/tool/dartdoc_compare.dart	💔 Not covered
pkgs/markdown/tool/expected_output.dart	💔 Not covered
pkgs/markdown/tool/stats.dart	💔 Not covered
pkgs/markdown/tool/stats_lib.dart	💔 Not covered
pkgs/markdown/tool/update_case_folding.dart	💔 Not covered
pkgs/markdown/tool/update_emojis.dart	💔 Not covered
pkgs/markdown/tool/update_entities.dart	💔 Not covered
pkgs/markdown/tool/update_github_emojis.dart	💔 Not covered

This check for test coverage is informational (issues shown here will not fail the PR).

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Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

This check can be disabled by tagging the PR with skip-changelog-check.

[srawlins]

Win!