Intent to implement & ship: CSS hyphenate-limit-chars property

[Jonathan Kew]

Summary: When applying automatic hyphenation, the optimal minimum number
of characters that should be required in the word, before the hyphen, or
after the hyphen can vary by the design of the page, or by the language.

This property allows finer grained control of hyphenation; in
particular, it enables authors to "dial back" the browser's readiness to
hyphenate so that it is used more sparingly.

I am aiming to implement & ship support for this property as of Firefox
136, or possibly 137 in case of complications.

There has been clear author interest in this property for some time, e.g.:
https://medium.com/clear-left-thinking/all-you-need-to-know-about-hyphenation-in-css-2baee2d89179#8434
https://justmarkup.com/articles/2019-01-28-a-look-at-css-hyphenation-in-2019/#too-much-hyphenation
https://generatedcontent.org/post/44751461516/finer-grained-control-of-hyphenation-with-css4

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1521723

Specification: https://drafts.csswg.org/css-text-4/#hyphenate-char-limits

Standards Body: CSS WG

Platform coverage: All

Preference: layout.css.hyphenate-limit-chars.enabled

DevTools bug: n/a

Other browsers:
    Blink:
        Shipped since Chrome 109
    WebKit:
        No signal (https://bugs.webkit.org/show_bug.cgi?id=67786)
        (Shipping old syntax properties
`hyphenate-limit-{before,after}` with the `-webkit-` prefix.)

web-platform-tests:
https://wpt.fyi/results/css/css-text?label=master&label=experimental&aligned&q=hyphenate-limit-chars
    (plus new interpolation tests to be landed as part of bug 1521723)

Mozilla reftests:
    layout/reftests/text/auto-hyphenation-* tests
        Many of these tests have updated behavior, since
hyphenate-limit-chars prevents use of some of the potential hyphenation
points.
        (Not in WPT because the details of where hyphenation can occur
are implementation-dependent; there are no precise rules or list of
supported languages specified.)


~ JK