Reviewed by Nikolas Zimmermann.

        This is a follow up to commit r56906. The fourth filter example,
        feMorphology, shouldn't be displayed. filterRes causes a scaling of the filter
        parameters, so that one value of 'radius' is lower than one.
        The spec want us to round filter values down and a value of zero
        for 'radius' stops the rendering process of feMorphology.

        * platform/mac/svg/filters/filterRes-expected.png:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@56969 268f45cc-cd09-0410-ab3c-d52691b4dbfc