Extend browsingContext.close params with promptUnload

[Lightning00Blade]

Closes #462

We already define this behavior on browser.close command. This PR extends this to the browsingContext.close as a parameter.
Default it chosen to not trigger prompting to unload with the idea that this is used more like resource cleanup rather then testing beforeUnload prompts and alike.

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[OrKoN]

LGTM (wait for other reviewers)

[OrKoN]

@juliandescottes @jgraham @whimboo would it be possible for you to review this one? it seems uncontroversial

[juliandescottes]

That looks fine to me, thanks

[OrKoN]

@jgraham should we land this change or do you have concerns about exposing this?

[thiagowfx]

Is there a bug or PR for the corresponding WPT test?

[jgraham]

I think this is OK in principle.

I also think we should fix this to not work by "magic" but actually modify https://html.spec.whatwg.org/#steps-to-fire-beforeunload to skip the prompt in some cases. It seems like we could reuse the existing WebDriver BiDi user prompt opened steps by allowing them to return a value that specifies whether to show the prompt or not, and keeping a set of browsing contexts for which the unload prompt should be skipped.

That doesn't block landing this one, but we should at least file an issue.

[Lightning00Blade]

Issue on HTML spec - whatwg/html#9890 , please add anything I may have missed.
Merging this per the last comment.

[whimboo]

@Lightning00Blade Thanks for your work! Are you going to also create a test for that?

[Lightning00Blade]

Yes I will add WPT test for it, I already updated Chromium-BiDi GoogleChromeLabs/chromium-bidi#1508 to support it, so it should be easier to create them now.

[whimboo]

Yes I will add WPT test for it, I already updated Chromium-BiDi GoogleChromeLabs/chromium-bidi#1508 to support it, so it should be easier to create them now.

Hi @Lightning00Blade. Quick question if you still have it in your queue. Thanks.

[whimboo]

FYI the tests will be added via web-platform-tests/wpt#44004.