Fixed: <rdar://problem/5815862> Opening a subclassed NSWindow from a Safari plugin causes Safari to crash on Quit
        
        This fix addresses crashes in both Silverlight and ChemDraw.  This type of crash would occur because AppKit still
        had a reference to open windows that the plugin created (which no longer exist). 
        
        * Plugins/WebNetscapePluginPackage.mm:
        (-[WebNetscapePluginPackage _unloadWithShutdown:]): Do not unload the plug-in bundle on browser shutdown. 



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@41634 268f45cc-cd09-0410-ab3c-d52691b4dbfc