Encode/decode CFURLRequestRefs when USE(CFNETWORK) is enabled

Encode/decode CFURLRequestRefs when USE(CFNETWORK) is enabled
https://bugs.webkit.org/show_bug.cgi?id=134454
<rdar://problem/17510980>

Reviewed by Andreas Kling.

Source/WebKit2:
Use new helper methods to serialize/deserialize CFURLRequestRef directly so we can avoid
creating NSURLRequest.

* Shared/mac/WebCoreArgumentCodersMac.mm:
(IPC::ArgumentCoder<ResourceRequest>::encodePlatformData):
(IPC::ArgumentCoder<ResourceRequest>::decodePlatformData):

WebKitLibraries:
* WebKitSystemInterface.h:
* libWebKitSystemInterfaceMavericks.a:
* libWebKitSystemInterfaceMountainLion.a:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@170685 268f45cc-cd09-0410-ab3c-d52691b4dbfc