DOM scroll event is UIEvent, but should be Event

[bradleyayers]

TypeScript Version: 2.4.0 / nightly (2.5.0-dev.201xxxxx)

Code

document.addEventListener("scroll", e => {
    e.view;
});

Expected behavior:

This should not type check, as view does not exist on Event. I ran into this because in Chrome (I tested on Chrome 60) event.view is undefined for scroll events. There's a Chromium issue from 2015 about emitting a UIEvent and is marked as WontFix, saying:

We intend to update the UIEvent spec to be consistent with this since we don't believe that anyone creates a UIEvent for 'scroll'.

The spec is updated and shows that scroll events should just be an Event rather than a UIEvent.

Actual behavior:

e is considered a UIEvent, which does have a view property, and so the code type checks successfully.

[cgatian]

I believe this should be closed