Reviewed by Adele Peterson.

        Add regression tests for autocorrection panel
        https://bugs.webkit.org/show_bug.cgi?id=47308
        <rdar://problem/8521243>

        Added regression tests for recently added autocorrection panel on Mac platform, as implemented in <https://bugs.webkit.org/show_bug.cgi?id=44958>.

        * editing/spelling/autocorrection-delete.html: Added.
        * editing/spelling/autocorrection-removing-underline-after-paste.html: Added.
        * editing/spelling/autocorrection-removing-underline.html: Added.
        * editing/spelling/autocorrection-simple.html: Added.
        * platform/mac-leopard/Skipped:
        * platform/mac-snowleopard/Skipped:
        * platform/mac-tiger/Skipped:
        * platform/mac-wk2/Skipped:
        * platform/mac/editing/spelling/autocorrection-delete-expected.checksum: Added.
        * platform/mac/editing/spelling/autocorrection-delete-expected.png: Added.
        * platform/mac/editing/spelling/autocorrection-delete-expected.txt: Added.
        * platform/mac/editing/spelling/autocorrection-removing-underline-after-paste-expected.checksum: Added.
        * platform/mac/editing/spelling/autocorrection-removing-underline-after-paste-expected.png: Added.
        * platform/mac/editing/spelling/autocorrection-removing-underline-after-paste-expected.txt: Added.
        * platform/mac/editing/spelling/autocorrection-removing-underline-expected.checksum: Added.
        * platform/mac/editing/spelling/autocorrection-removing-underline-expected.png: Added.
        * platform/mac/editing/spelling/autocorrection-removing-underline-expected.txt: Added.
        * platform/mac/editing/spelling/autocorrection-simple-expected.checksum: Added.
        * platform/mac/editing/spelling/autocorrection-simple-expected.png: Added.
        * platform/mac/editing/spelling/autocorrection-simple-expected.txt: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@69269 268f45cc-cd09-0410-ab3c-d52691b4dbfc