Re-adds the loop that enforces that line breaks never point at empty inlines that was originally added in https://codereview.chromium.org/42803002. This
fixes the regression introduced by the refactor in
https://codereview.chromium.org/66043002. Also fixes the broken unit test that
ought to have caught this regression in the first place :-(

BUG=322937

Review URL: https://codereview.chromium.org/104023008

git-svn-id: svn://svn.chromium.org/blink/trunk@163231 bbb929c8-8fbe-4397-9dbb-9b2b20218538