Reviewed by Dimitri Glazkov.

        Add some missing pixel results for compositing tests.

        * platform/mac/compositing/layers-inside-overflow-scroll-expected.checksum: Added.
        * platform/mac/compositing/layers-inside-overflow-scroll-expected.png: Added.
        * platform/mac/compositing/overflow/overflow-scroll-expected.checksum: Added.
        * platform/mac/compositing/overflow/overflow-scroll-expected.png: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@45442 268f45cc-cd09-0410-ab3c-d52691b4dbfc