Reviewed by Martin Robinson.

        [GTK] Split webkitprivate.{cpp,h} in more manageable chunks
        https://bugs.webkit.org/show_bug.cgi?id=50698

        Split private bits of several objects to their own private
        headers, and to their implementation files.

        * GNUmakefile.am:
        * WebCoreSupport/ChromeClientGtk.cpp:
        * WebCoreSupport/EditorClientGtk.cpp:
        * WebCoreSupport/FrameLoaderClientGtk.cpp:
        (WebKit::FrameLoaderClient::dispatchWillSendRequest):
        * webkit/webkitdownload.cpp:
        (webkit_download_set_response):
        * webkit/webkitdownloadprivate.h: Added.
        * webkit/webkithittestresult.cpp:
        (WebKit::kit):
        * webkit/webkithittestresultprivate.h: Added.
        * webkit/webkitnetworkresponse.cpp:
        (WebKit::core):
        (WebKit::kitNew):
        * webkit/webkitnetworkresponseprivate.h: Added.
        * webkit/webkitprivate.cpp:
        * webkit/webkitprivate.h:
        * webkit/webkitsecurityorigin.cpp:
        (webkit_security_origin_get_web_database):
        (WebKit::core):
        (WebKit::kit):
        * webkit/webkitsecurityoriginprivate.h: Added.
        * webkit/webkitviewportattributes.cpp:
        * webkit/webkitviewportattributesprivate.h: Added.
        * webkit/webkitwebbackforwardlist.cpp:
        * webkit/webkitwebbackforwardlistprivate.h: Added.
        * webkit/webkitwebdatabase.cpp:
        * webkit/webkitwebframe.cpp:
        (webkit_web_frame_get_network_response):
        * webkit/webkitwebhistoryitem.cpp:
        * webkit/webkitwebhistoryitemprivate.h: Added.
        * webkit/webkitwebnavigationaction.cpp:
        (WebKit::kit):
        (WebKit::core):
        * webkit/webkitwebnavigationactionprivate.h: Added.
        * webkit/webkitwebpolicydecision.cpp:
        * webkit/webkitwebpolicydecisionprivate.h: Added.
        * webkit/webkitwebresource.cpp:
        * webkit/webkitwebresourceprivate.h: Added.
        * webkit/webkitwebsettings.cpp:
        * webkit/webkitwebsettingsprivate.h: Added.
        * webkit/webkitwebview.cpp:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@73855 268f45cc-cd09-0410-ab3c-d52691b4dbfc