tryHyphenating() assumes that the character at lastSpace is a space character, and doesn’t include it in the string passed to lastHyphenLocation(). This is not always the case, such as when the current word is the first on a line. Patch forthcoming.
Created attachment 63826 [details]
Include the character at lastSpace in the string passed to lastHyphenLocation()
Fixed in <http://trac.webkit.org/changeset/64920>.