Reviewed by Dan Bernstein.

        Move instantiatePlugin to NetscapePluginHostManager.
        
        * Plugins/Hosted/NetscapePluginHostManager.h:
        * Plugins/Hosted/NetscapePluginHostManager.mm:
        (WebKit::NetscapePluginHostManager::instantiatePlugin):
        * Plugins/Hosted/NetscapePluginHostProxy.h:
        * Plugins/Hosted/NetscapePluginHostProxy.mm:
        * Plugins/Hosted/WebHostedNetscapePluginView.mm:
        (-[WebHostedNetscapePluginView createPlugin]):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@38883 268f45cc-cd09-0410-ab3c-d52691b4dbfc