[uievents] The `resize` event isn't a UIEvent (#76)

In Safari, Firefox, and Chrome, [`resize`](https://w3c.github.io/uievents/#event-type-resize) events are instances of `Event`, not of `UIEvent` as this spec currently claims. Only MS Edge currently uses `UIEvent` for `resize`.

Also, CSSOM View specifies `resize` as a plain `Event`. Per https://drafts.csswg.org/cssom-view/#resizing-viewports :
> [...] *fire an event named `resize`* at the Window object associated with doc

And per https://dom.spec.whatwg.org/#concept-event-fire
> To "fire an event named e" means that a new event using the `Event` interface, [...]

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/uievents/issues/76