Reviewed by Ada.

    Reviewed by Ada.

        Add platform-specific constructor/destructor to ContextMenu so we can
        properly retain/release the platform menu description.

        * platform/ContextMenu.h:
        (WebCore::ContextMenu::platformDescription):
        * platform/mac/ContextMenuMac.mm:
        (WebCore::ContextMenu::ContextMenu):
        (WebCore::ContextMenu::~ContextMenu):
        (WebCore::getNSMenuItem):
        (WebCore::ContextMenu::appendItem):
        (WebCore::ContextMenu::itemCount):
        (WebCore::ContextMenu::insertItem):
        (WebCore::ContextMenu::setPlatformDescription):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@17917 268f45cc-cd09-0410-ab3c-d52691b4dbfc