<rdar://problem/4602408> -webkit-highlight needs to support images and elements other than text

        * rendering/RenderBox.cpp:
        (WebCore::RenderBox::paintCustomHighlight):
        * rendering/RenderBox.h:
        Utility for subclasses.
        
        * rendering/RenderImage.cpp:
        (WebCore::RenderImage::paint):
        Custom highlight in front of images.
        
        * rendering/RenderListMarker.cpp:
        (WebCore::RenderListMarker::paint):
        Custom highlight in front of list markers.

        * rendering/RenderWidget.cpp:
        (WebCore::RenderWidget::paint):
        Custom highlight in front of objects.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@15320 268f45cc-cd09-0410-ab3c-d52691b4dbfc