Also fixed some rare dragging weirdness in WebHTMLView. If you attempted to drag a plug-in after dragging an image, the image would drag again.

        * Plugins.subproj/WebBaseNetscapePluginView.m:
        (-[WebBaseNetscapePluginView mouseDragged:]): subclass and do nothing to prevent calling mouseDragged in WebHTMLView
        (-[WebBaseNetscapePluginView performKeyEquivalent:]): no changes to this method, removed menuForEvent, wasn't needed after all
        * Plugins.subproj/WebNetscapePluginStream.m:
        (-[WebNetscapePluginStream stop]): minor clean-up


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@2388 268f45cc-cd09-0410-ab3c-d52691b4dbfc