Reviewed by Brady Eidson.

    Reviewed by Brady Eidson.

        https://bugs.webkit.org/show_bug.cgi?id=30260
        <rdar://problem/6447115> REGRESSION: Logging out from SAP doesn't work

        Tests: http/tests/xmlhttprequest/logout.html
               http/tests/xmlhttprequest/re-login-async.html
               http/tests/xmlhttprequest/re-login.html

        Fix several issues with existing credential handling code.

        * platform/network/CredentialStorage.cpp:
        (WebCore::pathToDefaultProtectionSpaceMap): Changed the data structure to a simpler one.
        (WebCore::originsWithCredentials): The reason for two-stage lookup above was that we didn't
        want to iterate paths for origins that never had credentials associated with them. Changed
        to use a separate HashSet for this.
        (WebCore::pathToDefaultProtectionSpaceMap): The concept of default per-path credentials didn't
        match the spec very well. UAs are supposed to deduce protection space from an URL, and then
        use whichever credentials are known for this protection space. So, OriginToDefaultBasicCredentialMap
        is now PathToDefaultProtectionSpaceMap.
        (WebCore::protectionSpaceMapKeyFromURL): Factored out a helper that extracts a directory
        URL from a given URL. These directory URLs are what we use as keys in PathToDefaultProtectionSpaceMap.
        (WebCore::CredentialStorage::set): Updated for above changes.
        (WebCore::findDefaultProtectionSpaceForURL): Factored out code iterating path length to find
        a prefix in OriginToDefaultBasicCredentialMap.
        (WebCore::CredentialStorage::set): Another version of set() can update credentials for a
        URL default protection space. It does nothing if the given URL doesn't correspond to a known
        protection space.
        (WebCore::CredentialStorage::get): Renamed from getDefaultAuthenticationCredential.

        * platform/network/CredentialStorage.h: Made the distinction between methods that use a known
        protection space and those that deduce one from URL more clear.

        * platform/network/mac/ResourceHandleMac.mm:
        (WebCore::ResourceHandle::start): Update credentials before starting the request for real.
        This makes the following pattern work:
          var req = new XMLHttpRequest("GET", "logout.html", "logout", "logout"); // wrong credentials
          req.send("");
          req.abort();
        Abort() is used here to avoid having UA present an auth dialog after getting a 401 response.
        Note that one cannot log in using the same method, because there isn't a known protection
        space for the URL yet in that case, so the added code has no effect.
        (WebCore::ResourceHandle::didReceiveAuthenticationChallenge): Use a correct persistence for
        calling receivedCredential(). This fixes logging in using an async XHR (withut abort(), of
        course), and matches sync case.
        (+[WebCoreSynchronousLoader loadRequest:allowStoredCredentials:returningResponse:error:]):
        Renamed getDefaultAuthenticationCredential() to get().

        * platform/network/cf/ResourceHandleCFNet.cpp:
        (WebCore::ResourceHandle::start):
        (WebCore::WebCoreSynchronousLoader::load):
        Same changes as in Mac code.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@49406 268f45cc-cd09-0410-ab3c-d52691b4dbfc