This works on Firefox too. And I would imagine most other browsers too.
Simply right-click the bookmark, select properties, and delete what is written in the "Name" box.
Accept, and you will be left with just the symbol.
This is handy for more bookmark space on the bar, I guess, but if you say, have two bookmarks to different links on the same webpage, it could get confusing.
And webpages which don't provide a symbol, and the browser gives it a blank page symbol, would not work at all.