• Properly allocate ports when debugging Chrome and Dartium in an IPv6-only
  environment.

• Add a retry option to test() and group() functions, as well
  as @Retry() annotation for test files and a retry
  configuration field for dart_test.yaml. A test with reties
  enabled will be re-run if it fails for a reason other than a
  TestFailure.

• Add a --no-retry runner flag that disables retries of failing tests.

• Fix a "concurrent modification during iteration" error when calling
  addTearDown() from within a tear down.

• Add a doesNotComplete matcher that asserts that a Future never completes.

• throwsA() and all related matchers will now match functions that return
  Futures that emit exceptions.

• Respect onPlatform for groups.

• Only print browser load errors once per browser.

• Gracefully time out when attempting to deserialize a test suite.

• Upgrade to package:matcher 0.12.1

• Now support v0.30.0 of pkg/analyzer

• The test executable now does a "hard exit" when complete to ensure lingering isolates or async code don't block completion. This may affect users trying to use the Dart service protocol or observatory.

• Refactor for internal tools.

• Introduce new flag --chain-stack-traces to conditionally chain stack traces.

• Fixed more blockers for compiling with dev_compiler.

• Dartfmt the entire repo.

• Note: 0.12.20+5-0.12.20+7 were tagged but not officially published.

More fixes for DDC

• Add type info to prevent DDC compile time failure