Reviewed by Nikolas Zimmermann.

        Tests to the filterRes implementation for SVG Filters
        [https://bugs.webkit.org/show_bug.cgi?id=6021]

        big-sized-filter: tests if filter quality is scaled down on a too
            big SourceImage (SourceGraphic, SourceAlpha)
        big-sized-filter-2: tests if the filter quality is scaled down
            on a too big filter effect size.
        filterRes: Various tests of SVG Filters with different values for
            filterRes attributes. Checks
            * that kernel values (if present) are scaled with the filterRes
            * subRegion calculation is correct for effects with deeper
              dependencies.

        * platform/mac/svg/filters/big-sized-filter-2-expected.txt: Added.
        * platform/mac/svg/filters/big-sized-filter-expected.checksum: Added.
        * platform/mac/svg/filters/big-sized-filter-expected.png: Added.
        * platform/mac/svg/filters/big-sized-filter-expected.txt: Added.
        * platform/mac/svg/filters/filterRes-expected.checksum: Added.
        * platform/mac/svg/filters/filterRes-expected.png: Added.
        * platform/mac/svg/filters/filterRes-expected.txt: Added.
        * svg/filters/big-sized-filter-2.svg: Added.
        * svg/filters/big-sized-filter.svg: Added.
        * svg/filters/filterRes.svg: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@51301 268f45cc-cd09-0410-ab3c-d52691b4dbfc