We should shuffle our tests. I've encountered a number of test files that depend on state set by previous tests. This ends up hiding bugs and/or creating unnecessary breaking changes later on when we have to fix it.

Package test takes an argument --test-randomize-ordering-seed=random. For regular test runs this looks like pub run test --test-randomize-ordering-seed=random. For flutter test we'll have to create a way to pipe in the argument. In general, we'll want to update dev/bots/test.dart to use this argument by default when running tests for CI.

/cc @jonahwilliams @goderbauer @tvolkert @Hixie @yjbanov @zanderso - I would not be surprised if this surfaces various breaking changes in tool/flutter/etc.