WebKit doesn’t recognize a line breaking opportunity between a slash and a latin character (e.g. after the slash in “before/after”), but the Unicode standard, specifically UAX #14, says that there is a line break opportunity there (see <http://www.unicode.org/reports/tr14/#SY>). The Unicode behavior allows long URLs to wrap better.
See also bug 37698.
Mitz also mentioned to me that a potential downside is that we'll wrap strings like "km/h", which can be particularly bad in table titles.
I think this bug could be solved once we implement line-break; anywhere and overflow-wrap: anywhere
As a matter of fact, I'm not sure whether this bug should be marked as FIXED. There are indeed breaking opportunities between a slash and a latin character by using the 'word-break: break-all' feature.
Attached a test case and the rendering result using trunk (r244730)
Created attachment 368590 [details]
Test case to reproduce the issue
Created attachment 368591 [details]