update some StreamController apis to Future<void> from Future<dynamic> (#198)

This is probably technically breaking for some cases - but it doesn't look to be breaking for anything at all internally, so I think in practice it is not breaking. Finishing up a global presubmit now with all the changes (but already did one with a subset).

WDYT?
2 files changed
tree: d2ec1ff459fab56247ec4552dd8886713d6d1607
  1. .github/
  2. lib/
  3. test/
  4. .gitignore
  5. AUTHORS
  6. CHANGELOG.md
  7. CONTRIBUTING.md
  8. LICENSE
  9. README.md
  10. analysis_options.yaml
  11. pubspec.yaml
README.md

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