When a dash separates two digits, it's very likely to not be a hyphen
inserted to split a word into two lines (e.g. "par\n-ser"), but rather
either a minus sign, a range, or a date. For example, in the tracemonkey
PDF there is `2008-02` (a date) split across two lines.
Preserving the dash, similarly to how we do for compound words, allows
searches for "2008-02" to find a match.