Reviewed by Gustavo Noronha.

        Workaround Java plugins not drawing themselves properly on first
        expose by doing a late size-allocate after 'plug-added' has been
        emitted on the embedding GtkSocket. It's unclear to me if this is
        a bug in our side or theirs, but this should be pretty safe and
        fixes the annoyance while we investigate it further.

        * plugins/gtk/PluginViewGtk.cpp:
        (WebCore::plugAddedCallback):
        (WebCore::PluginView::platformStart):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@55238 268f45cc-cd09-0410-ab3c-d52691b4dbfc