Remove obsolete FormDataStreamMac code

    Remove obsolete FormDataStreamMac code
        https://bugs.webkit.org/show_bug.cgi?id=82244

        Reviewed by Brady Eidson.

        * platform/network/ResourceHandle.h:
        Removed ResourceHandle::didSendBodyDataDelegateExists().

        * platform/network/mac/FormDataStreamMac.h:
        * platform/network/mac/FormDataStreamMac.mm:
        Removed code that was needed to call ResourceLoaderClient::didSendData() before Foundation
        added support for it.

        * platform/network/mac/ResourceHandleMac.mm:
        (WebCore::ResourceHandle::start):
        (WebCore::ResourceHandle::cancel):
        (-[WebCoreResourceHandleAsDelegate connection:willSendRequest:redirectResponse:]):
        (-[WebCoreResourceHandleAsDelegate connectionDidFinishLoading:]):
        (-[WebCoreResourceHandleAsDelegate connection:didFailWithError:]):
        We no longer need to associate streams with ResourceHandles!

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@112162 268f45cc-cd09-0410-ab3c-d52691b4dbfc