Replace the usage of `expect` and similar functions from `package:matcher` to `package:checks` equivalents.
Install
npx skills add flutter/agent-plugins --skill dart-migrate-to-checks-packagenpx skills add flutter/agent-plugins --skill dart-migrate-to-checks-package -a claude-code -gnpx skills add flutter/agent-plugins --skill dart-migrate-to-checks-package -a codex -ggemini skills install https://github.com/flutter/agent-plugins.git --path skills/dart-migrate-to-checks-packagegh skill install flutter/agent-plugins dart-migrate-to-checks-packagegit clone --depth 1 https://github.com/flutter/agent-plugins /tmp/flutter__agent-plugins
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/flutter__agent-plugins/skills/dart-migrate-to-checks-package ~/.claude/skills/dart-migrate-to-checks-package # Claude Code
cp -R /tmp/flutter__agent-plugins/skills/dart-migrate-to-checks-package ~/.agents/skills/dart-migrate-to-checks-package # Codex, Cursor, Gemini CLI, Copilot, OpenCode