See the attached test case. The first line of the list item doesn't break in the right place and overflows the div.
Created attachment 13135 [details] Test case
Created attachment 13138 [details] Patch, including change log and layout test No layout test regressions.
Comment on attachment 13138 [details] Patch, including change log and layout test r=me
<rdar://problem/4993465>
r19601