Reviewed by Kenneth Russell.

        [CHROMIUM] Unskip the failing tests in chromium-gpu, and adjust the
        expectations to match reality.
        https://bugs.webkit.org/show_bug.cgi?id=48473
        
        Some bugs were already fixed and the test lines could be removed, some
        tests have started newly-failing.  Rebaselined one test that had a bad
        checksum.

        * platform/chromium-gpu-linux/compositing/iframes/composited-iframe-alignment-expected.checksum: Added.
        * platform/chromium-gpu-linux/compositing/iframes/composited-iframe-alignment-expected.png: Added.
        * platform/chromium-gpu-linux/compositing/iframes/composited-iframe-alignment-expected.txt: Added.
        * platform/chromium-gpu/test_expectations.txt:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@70735 268f45cc-cd09-0410-ab3c-d52691b4dbfc