[css-text-3][css-text-4] Japanese small kana and `line-break: normal`

[fantasai]

It turns out that WebKit has been shipping a prohibition against breaks before small kana for awhile. But only sometimes: it depends on whether the language is tagged or not, see testcase. Tagged content is looser, untagged content is stricter. Firefox afaict never allows breaks before small kana.

I think this opens up the question of, should we reconsider defaulting line-break: normal to prohibiting breaks before small kana? Since it seems to be Web-compatible to change, would that be more natural for Japanese?

[fantasai]

https://www.w3.org/TR/css-text-3/#line-break-property

Proposed text would be

Option A: Allow either behavior in normal.

The following breaks are forbidden in strict line breaking and allowed in normal and loose:
breaks before Japanese small kana or the Katakana-Hiragana prolonged sound mark, i.e. characters from the Unicode line breaking class CJ. [UAX14]

Option B: Forbid breaks before small kana in normal.

The following breaks are forbidden in strict and normal line breaking and allowed in normal and loose:
breaks before Japanese small kana or the Katakana-Hiragana prolonged sound mark, i.e. characters from the Unicode line breaking class CJ. [UAX14]

[frivoal]

I think you are right that this would be an improvement. I have no strong preference between A and B. B should lead to more interop, so maybe that one?

[jfkthame]

B should lead to more interop

I think it also promises better behavior in the common/default case. A break before small kana is generally undesirable, so it should only be allowed if an author explicitly opts in to the "looser" behavior, and not when such characters appear in unstyled, untagged content.