Enable layout.css.text-autospace.enabled in all channels

Initially, the CSS text-autospace will be implemented behind the preference layout.css.text-autospace.enabled. After the layout rendering is ready, we can enable it in all channels in this bug.

Once enabled, this should be documented on MDN and added to the BCD. And it's also worth a release note, I think.

[Why is this notable]: Gives authors control over the spacing between adjacent characters.
[Affects Firefox for Android]: yes
[Suggested wording]: Implemented support for the text-autospace property, which provides authors control over the spacing between adjacent characters, allowing for automatic control over spacing between different scripts and around punctuation.
[Links (documentation, blog post, etc)]:
https://drafts.csswg.org/css-text-4/#text-autospace-property

Sebastian

No longer blocked - all dependencies resolved.

That is, enable layout.css.text-autospace.enabled by default.

We are planning to ship text-autospace in Firefox 146, where the 146 Nightly starts on Oct 13 https://whattrainisitnow.com/calendar/

I noticed that in bug 1987997, the default value was changed from normal to no-autospace. Was this done for performance reasons? Is there more performance test data available to share?

(In reply to 一丝 from comment #5)

I noticed that in bug 1987997, the default value was changed from normal to no-autospace. Was this done for performance reasons? Is there more performance test data available to share?

Yes, we've seen performance regressions across several test suites in bug 1991421, bug 1991423, bug 1991424, bug 1991689. Even with the effort in bug 1989128, bug 1989851, bug 1991943 and bug 1991689, we still couldn't mitigate all of them. Also, using no-autospace as the default value is also compatible with blink and webkit.

[Edit: added two additional bugs that optimized the text-autospace performance.]

https://hg.mozilla.org/mozilla-central/rev/46be69544262

firefox-beta Uplift Approval Request

• User impact if declined: No user impact if we are not shipping text-autospace in Firefox 145, but we'd like the feature to gain more exposure. See also the uplift request in bug 1987997.
• Code covered by automated testing: yes
• Fix verified in Nightly: yes
• Needs manual QE test: no
• Steps to reproduce for manual QE testing:
• Risk associated with taking this patch: low
• Explanation of risk level: If combining the uplifted patch in Bug 1987997, auto-spacing is not applied by default on web pages, making the risk lower.
• String changes made/needed: N/A
• Is Android affected?: yes

That is, enable layout.css.text-autospace.enabled by default.

Original Revision: https://phabricator.services.mozilla.com/D264365

MDN docs changes can be tracked in the following GitHub issue https://github.com/mdn/content/issues/41501

Added to our final 145 release notes.