Add gdk version of ContextMenuClient based on qt version.

        * WebCoreSources.bkl:
        * page/gdk/ContextMenuClientGdk.cpp: Added.
        (WebCore::ContextMenuClientGdk::contextMenuDestroyed):
        (WebCore::ContextMenuClientGdk::getCustomMenuFromDefaultItems):
        (WebCore::ContextMenuClientGdk::contextMenuItemSelected):
        (WebCore::ContextMenuClientGdk::downloadURL):
        (WebCore::ContextMenuClientGdk::copyImageToClipboard):
        (WebCore::ContextMenuClientGdk::searchWithGoogle):
        (WebCore::ContextMenuClientGdk::lookUpInDictionary):
        (WebCore::ContextMenuClientGdk::speak):
        (WebCore::ContextMenuClientGdk::stopSpeaking):
        * page/gdk/ContextMenuClientGdk.h: Added.
        * webcore-base.bkl: curl is needed when building webcore_base files.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@19647 268f45cc-cd09-0410-ab3c-d52691b4dbfc