Reviewed by Antti Koivisto. 

        <rdar://problem/6886382> REGRESSION (Safari 4PB -> ToT): HTTP cache revalidation broken.

        This was caused in http://trac.webkit.org/changeset/41425, which fixed an image caching bug
        in QuickLooks (rdar://problem/6619630).

        We need to respect the DocumentLoader's request cache policy when deciding the cache policy
        for subresources, but the check (originally removed in r39304 and added back in in the same
        place in r41424) needs to be tweaked and relocated a bit.

        * loader/FrameLoader.cpp:
        (WebCore::FrameLoader::subresourceCachePolicy): Renamed from cachePolicy().  Move checking
          the DocumentLoader's request to a more appropriate place. Add code to handle the recently 
          added FIXME regarding POSTs. Add a new FIXME describing a great way to make this code 
          cleaner in the future.
        * loader/FrameLoader.h:

        * loader/DocLoader.cpp:
        (WebCore::DocLoader::cachePolicy): Calls the newly renamed subresourceCachePolicy().



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@43878 268f45cc-cd09-0410-ab3c-d52691b4dbfc