[css-text-4] hyphenate-limit-lines should either disallow negative integers or explain what they do #12517

The hyphenate-limit-lines property, https://www.w3.org/TR/css-text-4/#propdef-hyphenate-limit-lines, currently allows both positive and negative integer values.

Likely, negative values should just be invalid (WebKit, for instance, disallows them in -webkit-hyphenate-limit-lines). If that is not the case, the spec should explain what they do.