Add “opener” function in the Window Module

[Woody88]

Hey guys, I noticed that the opener function is not in the Window module.

Here is the link:
https://developer.mozilla.org/en-US/docs/Web/API/Window/opener

I can make a PR for it if you will accept it.
Please let me know!

[jonathanlking]

Closely related, we are also missing Window.parent and Window.frames.

I imagine the suitable type for parent would be parent :: Window -> Effect Window however frames would be slightly more difficult/interesting 😸 (as according to the docs it's not an actual array).

[garyb]

If it appears in the spec, we'll accept it 🙂 (https://www.w3.org/TR/html5)

• opener is there, typed as any which is a little unfortunate - so it'd be Foreign here I guess
• the suggested parent implementation sounds good
• frames is a WindowProxy (which for the purposes of us is just Window again), it seems like we need a function to index the frames on a Window, along with the length

[jonathanlking]

From the spec:

The opener IDL attribute on the Window object, on getting, must return the WindowProxy object of the browsing context from which the current browsing context was created (its opener browsing context), if there is one, if it is still available, and if the current browsing context has not disowned its opener; otherwise, it must return null.

In this spirit, would you be happy with opener :: Window -> Effect (Maybe Window), rather than Foreign?

(Thanks for the feedback!)

Edit: opener should take a Window as an argument

[garyb]

That's strange, since they do usually have a nullable? annotation in the IDLs, maybe it's because this is settable as well as gettable. But yep, that sounds like a much better type 😄.