[css3-text] katakana-hiragana prolonged sound mark

the definition of line-break includes a specific rule for U+30FC
(KATAKANA-HIRAGANA PROLONGED SOUND MARK) but does not call out behavior for
the halfwidth variant of this character, U+FF70; however, UAX #14 (version
6.1) [2] includes both of these in the CJ property set; is this an
oversight or intentional? if the latter, what is the reason and perhaps a
note should be added to [1]

[1] http://dev.w3.org/csswg/css3-text/#line-break
[2] http://www.unicode.org/Public/UNIDATA/LineBreak.txt