1465592 - Enable Shadow DOM unconditionally in chrome documents

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, task, P3)

Description

[Brian Grinstead [:bgrins]]

I'd like to start testing out usage of Shadow DOM with our Custom Elements in the browser chrome.

Right now `mIsShadowDOMEnabled = nsContentUtils::IsShadowDOMEnabled();` [0] which is keyed off of the "dom.webcomponents.shadowdom.enabled" pref.

For Custom Elements we updated the CustomElementRegistry::IsCustomElementEnabled check to include a principle check [1] and make it always on. I think we could do the same here.

[0]: https://searchfox.org/mozilla-central/rev/5a744713370ec47969595e369fd5125f123e6d24/dom/base/nsDocument.cpp#2124 [1]: [1]: https://searchfox.org/mozilla-central/rev/5a744713370ec47969595e369fd5125f123e6d24/dom/base/CustomElementRegistry.cpp#293

Comment 1

[Brian Grinstead [:bgrins]]

Attachment: Bug 1465592 - Enable Shadow DOM unconditionally in chrome documents

Review commit: https://reviewboard.mozilla.org/r/248236/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/248236/

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

I'm not quite sure whether Shadow DOM is ready enough for being enabled always in browser chrome.

Comment 3

[Brian Grinstead [:bgrins]]

(In reply to Olli Pettay [:smaug] from comment #2)
> I'm not quite sure whether Shadow DOM is ready enough for being enabled
> always in browser chrome.

OK, good to know - this isn't urgent. Are there any particular bugs we should block this on?

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

Mostly just generic stability. Custom Elements had been enabled in Nightly for months before it was enabled always for chrome.

From https://bugzilla.mozilla.org/showdependencytree.cgi?id=1205323&hide_resolved=1
focus handling stuff probably needs still some small tweaks and directionality stuff is unclear.
I assume without proper directionality support, FF UI would be broken on rtl locales.
Directionality depends on spec issues to be sorted out.

Comment 5

[Brian Grinstead [:bgrins]]

Alright, we'll put this bug on hold until we get the green light to start using it.

Comment 6

[ExE Boss]

Well, Web Components (Shadow DOM and Custom Elements) will be shipping in Firefox 63 stable, so this can probably be done now.

Comment 7

[Brian Grinstead [:bgrins]]

(In reply to ExE Boss from comment #6)
> Well, Web Components (Shadow DOM and Custom Elements) will be shipping in
> Firefox 63 stable, so this can probably be done now.

I'm not sure that the directionality stuff listed in Comment 4 has been resolved, though. Olli - is there a particular spec issue / bug to follow for that?

Comment 8

[Olli Pettay [:smaug][[e-mail]]]

Directionality stuff isn't fixed in the spec level, but we have implementation which tries to mimic other browsers in common cases. But it is expected that all the browsers will need to change their behavior, since what the implementations do atm isn't what people seem to want.

https://github.com/whatwg/html/issues/3699

Comment 9

[Brian Grinstead [:bgrins]]

Attachment: Bug 1465592 - Enable Shadow DOM unconditionally in chrome documents;r=smaug

Comment 10

[Brian Grinstead [:bgrins]]

Comment on attachment 8982293 [details]
Bug 1465592 - Enable Shadow DOM unconditionally in chrome documents

Moved this to phab and added a test. :smaug, I'll leave it up to you as far as when you are comfortable with us using this so feel free to clear the review for now if you aren't.

Comment 11

[Olli Pettay [:smaug][[e-mail]]]

Comment on attachment 9010316 [details]
Bug 1465592 - Enable Shadow DOM unconditionally in chrome documents;r=smaug

Olli Pettay [:smaug] (r- if the bug doesn't explain what the change(s) are about.) has approved the revision.

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/80ccc40bdd0a
Enable Shadow DOM unconditionally in chrome documents;r=smaug

Comment 13

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/80ccc40bdd0a

Comment 14

[ExE Boss]

Will this be uplifted to Firefox 63?

Comment 15

[Brian Grinstead [:bgrins]]

(In reply to ExE Boss from comment #14)
> Will this be uplifted to Firefox 63?

No. We aren't shipping any Shadow DOM in the chrome in 63.