BUILD FIX (r146088): ResourceRequest::cfURLRequest() is defined twice on iOS
<http://webkit.org/b/112387>

* platform/network/mac/ResourceRequestMac.mm:
(WebCore::ResourceRequest::cfURLRequest): Move method into
!USE(CFNETWORK) section since it's also defined in
cf/ResourceRequestCFNet.cpp on iOS.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146177 268f45cc-cd09-0410-ab3c-d52691b4dbfc