Resolve null safety migration TODOS (#135)

- Switch from `StackTrace.fromString` to `AsyncError.defaultStackTrace`.
- Remove a TODO about non-nullable `StackTrace`, by the time we merged
  null safety the type was already non-nullable and the TODO was stale.

Style tweak - remove the argument names from a Function type that are
redundant against their type names.
2 files changed
tree: dca3dfafe2b190b6a74c54d6cd74863bac5bedad
  1. .gitignore
  2. .test_config
  3. .travis.yml
  4. AUTHORS
  5. CHANGELOG.md
  6. CONTRIBUTING.md
  7. LICENSE
  8. README.md
  9. analysis_options.yaml
  10. lib/
  11. pubspec.yaml
  12. test/
README.md

Contains utility classes in the style of dart:async to work with asynchronous computations.