Docs on orderedByCompletionUnless give incorrect explanation of what cancellation does

[Strilanc]

The doc comment on orderedByCompletionUnless incorrectly says that the resulting future is cancelled if the given token is cancelled. The result isn't even a future. The actual behavior is that all futures in the array, that haven't completed yet, fail with cancellations.

Also: "the result fails with fails with a cancellation." Two fails withs.