Reviewed by Adam.

    Reviewed by Adam.

        - moving towards use of FrameLoader cross-platform; get FrameLoader.h
          and FrameLoader.cpp mostly ready

        * WebCore.xcodeproj/project.pbxproj: Added FrameLoader.cpp and
        FormState.cpp. Removed WebFormState.mm.

        * loader/FrameLoader.h: Put in lots of #if statements to see if we can
        get this header compiling on non-Mac.
        * loader/FrameLoader.cpp: Added. Has non-Mac-specific bits of FrameLoader.
        * loader/mac/FrameLoader.mm: Moved some non-Mac-specific bits out.

        * loader/FrameLoaderClient.h: Added some ifdefs.
        * loader/WebDocumentLoader.h: Ditto.
        * loader/WebLoader.h: Ditto.
        * loader/WebMainResourceLoader.h: Ditto.

        * loader/mac/WebDocumentLoader.mm:
        (WebCore::DocumentLoader::isLoadingInAPISense):
        Rewrote to work without bridge, partly to remove the need for ObjC
        bridge type in the header, and also because we're tearing down the bridge.

        * loader/mac/WebMainResourceLoader.mm:
        (WebCore::MainResourceLoader::MainResourceLoader): Removed unused
        m_contentLength and m_bytesReceived.
        (WebCore::MainResourceLoader::didReceiveResponse): Ditto.
        (WebCore::MainResourceLoader::didReceiveData): Ditto.

        * bridge/mac/WebCoreFrameBridge.h: Removed doneProcessingData.
        * bridge/mac/WebCoreFrameBridge.mm: Ditto.

        * loader/mac/FormState.mm: Removed.
        * loader/FormState.cpp: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@17429 268f45cc-cd09-0410-ab3c-d52691b4dbfc