Revert change of visible behavior in `CancelableOperation`. (#208)

* Revert change of visible behavior in `CancelableOperation`.

A prior change made it so that a `.then` on a `CancelableOperation`
would call the `onValue`/`onError` callback even if the
returned operation was cancelled beteen the time of the `then`
and the time the original operation completed.
The result would not show up in the cancelled operation,
but the callbacks would run.

This change blocks calling the callbacks if the returned operation
has been cancelled.
2 files changed
tree: 7b22580930e97564213ac5ec996a5723067edb38
  1. .github/
  2. lib/
  3. test/
  4. .gitignore
  5. analysis_options.yaml
  6. AUTHORS
  7. CHANGELOG.md
  8. CONTRIBUTING.md
  9. LICENSE
  10. pubspec.yaml
  11. README.md
README.md

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