https://bugs.webkit.org/show_bug.cgi?id=49094 added the test and it's failing on mac. I'm going to add to the Skipped list while I debug (need to spin up a mac build).
This passes on Leopard, so I moved the Skipped to the snow-leopard subdir. It's passing on GTK+ and QT as well. I only have Leopard, so I can't debug any further. There are lots of plugin specific entries in snow-leopard/Skipped, so maybe this is expected?
Original change that added skipped: http://trac.webkit.org/changeset/71552 Followup where I made it SL specific: http://trac.webkit.org/changeset/71558
ie., this might be https://bugs.webkit.org/show_bug.cgi?id=36462
Snow Leopard has out of process plug-ins, so results are often different. But it's certainly not a general expectation that tests fail.
Mass closing plug-in bugs, as plug-in support has been removed from WebKit. Please comment and/or reopen if this still affects WebKit in some way.