Reviewed by David Kilzer.

        Remove unnecessary test results.
        https://bugs.webkit.org/show_bug.cgi?id=47711

        The following tests were converted to dumpAsText() in
        http://trac.webkit.org/changeset/47608. So corresponding PNG files
        are unnecessary.
         - editing/execCommand/italicizeByCharacter.html
         - editing/execCommand/modifyForeColorByCharacter.html
         - editing/execCommand/strikethroughSelection.html

        The following tests were converted to dumpAsText() in
        http://trac.webkit.org/changeset/47543.
         - editing/style/remove-underline-across-paragraph.html
         - editing/style/remove-underline-across-paragraph-in-bold.html

        The following tests were converted to dumpAsText() in
        http://trac.webkit.org/changeset/47542.
         - editing/style/remove-underline-after-paragraph.html
         - editing/style/remove-underline-after-paragraph-in-bold.html

        * platform/mac/editing/execCommand/italicizeByCharacter-expected.png: Removed.
        * platform/mac/editing/execCommand/modifyForeColorByCharacter-expected.png: Removed.
        * platform/mac/editing/execCommand/strikethroughSelection-expected.png: Removed.
        * platform/mac/editing/style/remove-underline-across-paragraph-expected.png: Removed.
        * platform/mac/editing/style/remove-underline-across-paragraph-in-bold-expected.png: Removed.
        * platform/mac/editing/style/remove-underline-after-paragraph-expected.png: Removed.
        * platform/mac/editing/style/remove-underline-after-paragraph-in-bold-expected.png: Removed.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@70431 268f45cc-cd09-0410-ab3c-d52691b4dbfc