Open the attached html page. The plugin has visibility:hidden, yet Safari draws it. This is with Safari 5, on 10.6.4.
Created attachment 65005 [details] test
Created attachment 65007 [details] test
*** Bug 60289 has been marked as a duplicate of this bug. ***
<rdar://problem/9391219>
This doesn't reproduce for me in Safari 6/ToT WebKit