WKBrowsingContextController should not be an API wrapper around WebPageProxy

https://bugs.webkit.org/show_bug.cgi?id=127454

Reviewed by Dan Bernstein.

* Shared/Cocoa/APIObject.mm:
(API::Object::newObject):
* Shared/mac/ObjCObjectGraphCoders.mm:
(WebKit::WebContextObjCObjectGraphDecoderImpl::decode):
* UIProcess/API/Cocoa/WKBrowsingContextController.mm:
(-[WKBrowsingContextController _initWithPageRef:]):
(+[WKBrowsingContextController _browsingContextControllerForPageRef:]):
* UIProcess/API/Cocoa/WKBrowsingContextControllerInternal.h:
* UIProcess/API/Cocoa/WKProcessGroup.mm:
(didNavigateWithNavigationData):
(didPerformClientRedirect):
(didPerformServerRedirect):
(didUpdateHistoryTitle):
* UIProcess/API/ios/WKContentView.mm:
(-[WKContentView browsingContextController]):
* UIProcess/API/mac/WKView.mm:
(-[WKView browsingContextController]):
* UIProcess/ios/WebPageProxyIOS.mm:
(WebKit::WebPageProxy::platformInitialize):
* UIProcess/mac/WebPageProxyMac.mm:
(WebKit::WebPageProxy::platformInitialize):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162580 268f45cc-cd09-0410-ab3c-d52691b4dbfc