Reviewed by Darin

    Reviewed by Darin

        - fixed <rdar://problem/5320208> WebKit should prevent Time Machine from backing up WebKit clients' icon databases

        * Misc/WebIconDatabase.mm:
        (-[WebIconDatabase init]):
        Re-added the code to exclude the icon database from backups. We now do this at the same time we (try to) import
        the old icon database format, which happens only once per icon database's lifetime.
        (-[WebIconDatabase _importToWebCoreFormat]):
        Assert that we haven't imported yet rather than bailing out. It's now the caller's responsibility to check
        whether we've imported yet.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@24117 268f45cc-cd09-0410-ab3c-d52691b4dbfc