https://bugs.webkit.org/show_bug.cgi?id=123512

Reviewed by Andreas Kling.

Also add a WKRemoteObjectInterface class that represents a remote object interface.

* Shared/API/Cocoa/WKRemoteObjectInterface.h: Added.
* Shared/API/Cocoa/WKRemoteObjectInterface.mm: Added.
(-[WKRemoteObjectInterface initWithProtocol:identifier:]):
(+[WKRemoteObjectInterface remoteObjectInterfaceWithProtocol:]):
* Shared/API/Cocoa/WKRemoteObjectRegistry.h: Added.
* Shared/API/Cocoa/WKRemoteObjectRegistry.mm: Added.
(-[WKRemoteObjectRegistry registerExportedObject:interface:]):
(-[WKRemoteObjectRegistry unregisterExportedObject:interface:]):
(-[WKRemoteObjectRegistry remoteObjectProxyWithInterface:]):
* WebKit2.xcodeproj/project.pbxproj:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@158274 268f45cc-cd09-0410-ab3c-d52691b4dbfc