Reviewed and landed by ap.

        Fixes one chunk of: http://bugzilla.opendarwin.org/show_bug.cgi?id=10604
        Provide stub implementation of RenderPopupMenuQt.

        * CMakeLists.txt:
        * platform/qt/RenderPopupMenuQt.cpp: Added.
        (WebCore::RenderPopupMenuQt::RenderPopupMenuQt):
        (WebCore::RenderPopupMenuQt::~RenderPopupMenuQt):
        (WebCore::RenderPopupMenuQt::clear):
        (WebCore::RenderPopupMenuQt::populate):
        (WebCore::RenderPopupMenuQt::showPopup):
        (WebCore::RenderPopupMenuQt::hidePopup):
        (WebCore::RenderPopupMenuQt::addSeparator):
        (WebCore::RenderPopupMenuQt::addGroupLabel):
        (WebCore::RenderPopupMenuQt::addOption):
        * platform/qt/RenderPopupMenuQt.h: Added.
        * platform/qt/RenderThemeQt.cpp:
        (WebCore::RenderThemeQt::systemFont):
        (WebCore::RenderThemeQt::createPopupMenu):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@16079 268f45cc-cd09-0410-ab3c-d52691b4dbfc