Type definition of CustomEvent constructor needs at least one parameter.
(The constructor of Event class also needs one parameter, actually.)

Since the current definition has no parameter, I encountered an error when I run a generated JS code by
Jasmine with node.

Following links are about CustomEvent class .
https://dom.spec.whatwg.org/#interface-customevent
https://developer.mozilla.org/en/docs/Web/API/CustomEvent

http://html5index.org/DOM%20-%20EventInit.html
http://html5index.org/DOM%20-%20CustomEventInit.html

I wrongly send a pull request #2007 on this issue.
Sorry about that.