PluginPackage::freeLibraryTimerFired asserts if plugin got loaded again meanwhile
https://bugs.webkit.org/show_bug.cgi?id=106463

Patch by David Faure <faure@kde.org> on 2013-01-10
Reviewed by Simon Hausmann.

No new tests, this code path will be tested by bug 106140.

* plugins/PluginPackage.cpp:
(WebCore::PluginPackage::freeLibraryTimerFired): skip unloading if loaded again meanwhile.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@139318 268f45cc-cd09-0410-ab3c-d52691b4dbfc