Change FrameTree to return Frames instead of LocalFrames.

Source/core/loader/FrameFetchContext.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 63 matching lines @@
             request.clearHTTPReferrer();
         else if (!request.httpReferrer())
             request.setHTTPReferrer(Referrer(outgoingReferrer, document->referrerPolicy()));
 
         FrameLoader::addHTTPOriginIfNeeded(request, AtomicString(outgoingOrigin));
     }
 
     if (isMainResource && m_frame->isMainFrame())
         request.setFirstPartyForCookies(request.url());
     else if (m_frame->tree().top()->isLocalFrame())
-        request.setFirstPartyForCookies(m_frame->tree().top()->document()->firstPartyForCookies());
+        request.setFirstPartyForCookies(toLocalFrame(m_frame->tree().top())->document()->firstPartyForCookies());
 
     // The remaining modifications are only necessary for HTTP and HTTPS.
     if (!request.url().isEmpty() && !request.url().protocolIsInHTTPFamily())
         return;
 
     m_frame->loader().applyUserAgent(request);
 
     // Default to sending an empty Origin header if one hasn't been set yet.
     FrameLoader::addHTTPOriginIfNeeded(request, nullAtom);
 }
@@ skipping 101 matching lines @@
     if (!response.isNull())
         dispatchDidReceiveResponse(ensureLoader(loader), identifier, response);
 
     if (dataLength > 0)
         dispatchDidReceiveData(ensureLoader(loader), identifier, 0, dataLength, 0);
 
     dispatchDidFinishLoading(ensureLoader(loader), identifier, 0, 0);
 }
 
 } // namespace WebCore