Add ability to create a WKErrorRef

Add ability to create a WKErrorRef
<rdar://problem/9115768>
https://bugs.webkit.org/show_bug.cgi?id=56279

Reviewed by Anders Carlsson.

Source/WebCore:

* WebCore.exp.in:
Add new exports.

* platform/network/cf/ResourceError.h:
* platform/network/cf/ResourceErrorCF.cpp:
(WebCore::ResourceError::platformCompare):
(WebCore::ResourceError::cfError):
(WebCore::ResourceError::operator CFErrorRef):
(WebCore::ResourceError::ResourceError):
(WebCore::ResourceError::cfStreamError):
(WebCore::ResourceError::operator CFStreamError):
* platform/network/mac/ResourceErrorMac.mm:
(WebCore::ResourceError::ResourceError):
(WebCore::ResourceError::platformCompare):
(WebCore::ResourceError::nsError):
(WebCore::ResourceError::operator NSError *):
(WebCore::ResourceError::cfError):
(WebCore::ResourceError::operator CFErrorRef):
Clean up ResourceError a bit and add ability to create a ResourceError from a CFErrorRef
regardless of whether CFNetwork is being used.

Source/WebKit2:

* Shared/API/c/cf/WKErrorCF.cpp: Added.
(WKErrorCreateWithCFError):
(WKErrorCopyCFError):
* Shared/API/c/cf/WKErrorCF.h: Added.
Add new API to create a WKErrorRef from a CFErrorRef
and vice-versa.

* WebKit2.xcodeproj/project.pbxproj:
* win/WebKit2.vcproj:
* win/WebKit2Generated.make:
Add new files.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@80981 268f45cc-cd09-0410-ab3c-d52691b4dbfc