Reviewed by Darin Fisher.

        Ensure that a cache policy that forces validation is cleared once
        the load event is fired, rather than only doing so at the next
        navigation. This leads to a lot of unnecessary load on AJAX-y
        websites.

        https://bugs.webkit.org/show_bug.cgi?id=41813

        Test: http/tests/xmlhttprequest/cache-headers-after-reload.html

        * loader/FrameLoader.cpp:
        (WebCore::FrameLoader::handledOnloadEvents): Reset m_loadType to FrameLoadTypeStandard.
        (WebCore::FrameLoader::addExtraFieldsToRequest): Only respect the original request's cache policy if the
            DocumentLoader is still loading, and handle the other cache policy settings that were scattered around the loader.
        (WebCore::FrameLoader::loadResourceSynchronously): Merge cachePolicy setting into FrameLoader::addExtraFieldsToRequest.
        * loader/SubresourceLoader.cpp:
        (WebCore::SubresourceLoader::create): Merge cachePolicy setting into FrameLoader::addExtraFieldsToRequest.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@63100 268f45cc-cd09-0410-ab3c-d52691b4dbfc