I previously made a PR (#136140) that used `switch` expressions to make some parts of the Flutter codebase easier to understand. It was assigned to the framework team, and @christopherfujino let me know that it was too large to effectively review and recommended breaking it up into smaller pull requests.

Here's a PR that only targets files in the `dev/` directory. Hopefully this will be easier to work with!

(solves issue https://github.com/flutter/flutter/issues/136139)