Update EventHandler.webidl

[KiChjang]

The WebIDL has more events defined on it now. Also, there is a new DocumentAndElementEventHandlers interface that is supposed to be defined on Document and HTMLElement.

Spec: https://html.spec.whatwg.org/multipage/webappapis.html#globaleventhandlers, https://html.spec.whatwg.org/multipage/webappapis.html#windoweventhandlers, https://html.spec.whatwg.org/multipage/webappapis.html#documentandelementeventhandlers
Code: components/script/dom/webidls/EventHandler.webidl, components/script/dom/webidls/HTMLElement.webidl, components/script/dom/webidls/Document.webidl

[s-baldrick]

@KiChjang
I'd like to have a go at this (though I'm unlikely to get started before Saturday).

Greetings,
Piotr

[jdm]

Great!

[Ms2ger]

Should we implement onfoo attributes where we never dispatch a foo event?

[jdm]

On one hand it's not great for feature detection. On the other hand, it's really easy to forget to add them when implementing code that dispatches the appropriate event, and it leads to frustrating and confusing debugging sessions. I lean towards adding the handlers for that reason.

[s-baldrick]

Hi, I've done a couple patches for this - https://github.com/s-baldrick/servo/tree/11158, and now I am trying to come up with some tests, although I am not sure what will be a sensible way of going about it since not all of these events will be triggered. I guess asserting if setting an event handler does not fail could be one way, but then they all get set in the same way, so testing for this might not bring much to the table. Do you have some suggestions about this?

[KiChjang]

You can actually open a PR right now, and I'll do a try run and see which tests it'll break. Some of our WPT tests are marked as FAILING, but after defining these events, I'd expect plenty of them to PASS.

[s-baldrick]

Cool, I'll open it this evening, as I am at work right now.