<rdar://problem/5074612> Added SPI to retrieve certificate info from a WebError.

    <rdar://problem/5074612> Added SPI to retrieve certificate info from a WebError.

        Reviewed by Steve.

        * Interfaces/IWebErrorPrivate.idl: Added IWebErrorPrivate
        * WebError.cpp:
        (WebError::QueryInterface): WebError now also implements IWebErrorPrivate
        (WebError::sslPeerCertificate): retrieves certificate info from CFError's user info.
        * WebError.h:
        * WebKit.vcproj/WebKitGUID.vcproj: Added IWebErrorPrivate_i.c

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@25299 268f45cc-cd09-0410-ab3c-d52691b4dbfc