Comment 3 for bug 771335

This is really easy to do by adding the text-overflow: ellipsis style to
the title of the overlay.

Unfortunately, the only major browser not to support text-overlay is
Firefox. Since we're depending on JS for this functionality anyway, we
can detect Firefox and clip the title string as needed and add ellipsis.

Here are screen shots of Chrome doing the sane thing with text-overflow
and of the JS ellipsifying in FF: http://imgur.com/a/ryCF3.