Reviewed by adele.
        
        Markers should clip to their viewport.
        http://bugzilla.opendarwin.org/show_bug.cgi?id=5967

        Test: svg/custom/marker-overflow-clip.svg

        * kcanvas/KCanvasResources.cpp:
        (WebCore::KCanvasMarker::KCanvasMarker):
        (WebCore::KCanvasMarker::setMarker):
        (WebCore::KCanvasMarker::draw):
        * kcanvas/KCanvasResources.h:
        (WebCore::KCanvasMasker::mask):
        * ksvg2/svg/SVGMarkerElement.cpp:
        (WebCore::SVGMarkerElement::SVGMarkerElement):
        (WebCore::SVGMarkerElement::parseMappedAttribute):
        (WebCore::SVGMarkerElement::canvasResource):
        (WebCore::SVGMarkerElement::createRenderer):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@16461 268f45cc-cd09-0410-ab3c-d52691b4dbfc