1450228 - Line breaking should not occur before IDEOGRAPHIC SPACE (U+3000)

Status: RESOLVED WORKSFORME

(Core :: Layout: Text and Fonts, defect, P3)

Description

[murakami]

Attachment: ideosp.html

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko/20100101 Firefox/61.0
Build ID: 20180329222832

Steps to reproduce:

Test firefox with the following html+css code (or attached ideosp.html):

```
<style>
p {
    width: 10em;
}
</style>
<p>あいうえおだろうか？　それは何のために！　私は、かきくけこだ。</p>
```



Actual results:

Line breaking occurs before IDEOGRAPHIC SPACE (U+3000), as follows:

```
あいうえおだろうか？
　それは何のために！
　私は、かきくけこ
だ。
```


Expected results:

Line breaking should not occur before IDEOGRAPHIC SPACE (U+3000).
This is important because IDEOGRAPHIC SPACE is normally used after "！" or "？" in the middle of a paragraph to keep 1em space after such punctuation marks as explained in JLREQ [3.1.6 Positioning of Dividing Punctuation Marks (Question Mark and Exclamation Mark) and Hyphens](https://www.w3.org/TR/jlreq/#positioning_of_dividing_punctuation_marks). 

IDEOGRAPHIC SPACE is classified as BA (Break After) in the UAX#14 http://unicode.org/reports/tr14/ and the line break opportunity should only exist after the character.
Other browsers (Chrome, Safari, Edge, IE11) conform to this line breaking rule.

Chrome and Safari result:
```
あいうえおだろう
か？　それは何のため
に！　私は、かきくけ
こだ。
```

Edge and IE11 result:
```
あいうえおだろうか？　
それは何のために！　
私は、かきくけこだ。
```

Comment 1

[murakami]

Which is better between Chrome/Safari and Edge/IE is a CSS Text issue:

[css-text-3] line breaks and ideographic space
https://github.com/w3c/csswg-drafts/issues/2500

Comment 2

[Makoto Kato [:m_kato]]

Even if I test this on Firefox 102 ESR, it works. Also, since we land bug 1719535, this doesn't also occur.