fast/frames/iframe-plugin-load-remove-document-crash.html crashed in WebNetscapePluginStream::destroyStreamWithReason on Leopard Intel Debug (Tests). See the URL. Unfortunately the crash log isn't available, perhaps due to some misconfiguration on the bots. (I've contacted Bill Siegrist about it.)
<rdar://problem/9121052>
*** Bug 56525 has been marked as a duplicate of this bug. ***
Maybe it is in connection with https://bugs.webkit.org/show_bug.cgi?id=63321.
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.