Reviewed by Maciej Stachowiak.

    Reviewed by Maciej Stachowiak.

        https://bugs.webkit.org/show_bug.cgi?id=24572
        XMLHttpRequest.statusText returns always "OK" on Mac

        Covered by existing tests, which now pass.

        * WebCore.base.exp:
        * platform/mac/WebCoreSystemInterface.h:
        * platform/mac/WebCoreSystemInterface.mm:
        Added a WebKitSystemInterface method to fetch status line.

        * platform/network/HTTPParsers.cpp: (WebCore::extractReasonPhraseFromHTTPStatusLine):
        * platform/network/HTTPParsers.h:
        * platform/network/cf/ResourceResponseCFNet.cpp: (WebCore::ResourceResponse::platformLazyInit):
        Moved code for parsing status line to HTTPHeaders, as it's used for both Mac and CF now.

        * platform/network/mac/ResourceResponseMac.mm: (WebCore::ResourceResponse::platformLazyInit):
        Use the actual reason phrase when available, and "OK" otherwise. Synthesizing a reson when
        there isn't one is misleading, so we'll stick to our old broken behavior on Tiger, rather than
        introduce a new broken one.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@57373 268f45cc-cd09-0410-ab3c-d52691b4dbfc