- If a data source can't be created for a plug-in request, don't create the frame or open a window.
	- cleaned up plug-in stream notifications

        * Plugins.subproj/WebBaseNetscapePluginView.h:
        * Plugins.subproj/WebBaseNetscapePluginView.m:
        (-[WebBaseNetscapePluginView initWithFrame:]): create streamNotifications dict
        (-[WebBaseNetscapePluginView dealloc]): release streamNotifications dict
        (-[WebBaseNetscapePluginView frameStateChanged:]): cleaned up
        (-[WebBaseNetscapePluginView loadRequest:inTarget:withNotifyData:]): create data source before frame
        * Plugins.subproj/WebPluginController.m:
        (-[WebPluginController showURL:inFrame:]): create data source before frame
        * WebView.subproj/WebControllerPrivate.m:
        (-[WebController _setTopLevelFrameName:]): don't allow _blank frames
        * WebView.subproj/WebFrame.m:
        (-[WebFrame findOrCreateFramedNamed:]): no need to check for _blank


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@2471 268f45cc-cd09-0410-ab3c-d52691b4dbfc