borisyankov/DefinitelyTyped — pull request #1391 by butlersoftware (2013-12-06 11:17:09+00:00)
Title: Fixed KnockoutComputed polymorphism

Previously it was difficult to do polymorphic/covariant hotness such as...
```javascript
function getSomething(): KnockoutObservable {
if (something) {
return ko.computed(...);
} else {
return ko.observable(...);
}
}
```
...because KnockoutComputed was not typed as a valid KnockoutObservable.

I updated KnockoutComputed to inherit from KnockoutObservable, therefore enabling this situation.