I thought the Mozilla solution required a plug-in.
Anyway, here's two workarounds in Safari:
1. Turn on tabs, and command-click (or middle-click) to open the link in a new tab.
It's not the same window, obviously, but it opens in the background, out of the way.
2. Make sure 'always show tab bar' is on in the prefs.
Drag-and-drop the link onto the tab that you're currently in. It will replace the current contents of the tab.
test link